Mice and monkeys, dogs and cats; The Biggest Pumpkin Ever, by Steven Kroll. Illustrated by Jeni Bassett. New York: Holiday House. Pages unnumbered. $12.95.; The Day the Teacher Went Bananas, by James Howe. Illustrated by Lillian Hoban. New York: E. P. Dutton. Pages unnumbered. $9.95.; Oh, Kojo! How Could You!, by Verna Aardema. Pictures by Marc Brown. New York: E. P. Dutton. Pages unnumbered. $10.95.; Mean Murgatroyd and the Ten Cats, by Nathan Zimelman. Illustrated by Tony Auth. New York: E. P. Dutton. Pages unnumbered. $9.95.

October 5, 1984

The following picture books center on animals as the main characters in stories which, for the most part, both entertain and guide. ''The Biggest Pumpkin Ever'' is surely one of the best Halloween books to have come along in a while. The two main characters (both mice) are colorfully and skillfully contrasted - one the product of relative sophistication and in-town living, the other a paunchy, simple field mouse. They fall in love with the same pumpkin seedling, having no knowledge of each other's feelings. One faithfully waters, loves, and nurtures the pumpkin by day, and the other does the same by night. Both strive for a magnificent hugeness, commensurate with the humility and depth of their parentlike dedication. The town mouse wants to win the local pumpkin contest and the field mouse longs to carve a jack-o'-lantern for Halloween. At first caring for the pumpkin independently, they learn of their mutual attachment when they bump into each other during the potential crisis of an early frost.

By the time they find a solution, the story has managed to convey a simple, convincing message of patience and persistence - with a deeper dimension, too. For the individual labors of these mice are not lost, but fulfilled when they cooperate in getting the pumpkin to the contest. (Of course they do get help from 100 fellow mice who tow it on motorcycles!)

''The Day the Teacher Went Bananas'' will have children howling with delight and asking for it to be read again and again. A kindergarten class gets a new teacher - a most unconventional one. He does his counting exercises on his bare toes, while ''conducting'' the attentive little learners in the same manner. He holds ''science'' class outside in the branches of a tree, and then breaks for a 16-banana lunch!

Yes, you guessed it. There was a mix-up, and the kids' real teacher, Mr. Quackerbottom (!), was mistakenly sent to the ape cage at the zoo, and you know who was assigned the task of pedagogue!

Children will ignite with cheers over this ''substitute'' teacher, and over the book's playful ironies throughout. Lillian Hoban's exceptional drawings win out again. And somehow, the affinities between the ape-teacher and the little ''monkeys'' in class are plausibly portrayed!

In ''Oh, Kojo! How Could You!'' Verna Aardema - a highly regarded storyteller - and award-winning illustrator Marc Brown, have teamed together to bring a most humorous Sudanese folk tale spectacularly to life. Children (aged 4 to 8) will also be enchanted with the various human characters: the evil and dishonest Ananse, symbolizing all that will deceive the unwary; the long-suffering mother, Tutuola; and the lazy, gullible son, Kojo.

The easily beguiled Kojo does indeed give all his mother's gold to the clever Ananse. Tutuola is certainly not enchanted by a dog Kojo buys from Ananse because he can supposedly fetch firewood all by himself. Nor is she taken with a cat who is said to be able to clear an entire compound of rats singlepaw-edly. Still, the cat and dog provide much more than just no work for Kojo: It's their rescue mission in pursuit of a most powerful magic ring that forms the basic excitement of the tale. And what comes to light at the end is a lazy boy's innate sense of well-meaning and, ironically, a kingly sense of right judgment.

The prose begs to be read aloud. It is melodious and rhythmic, and the frequent interspersion of thrice-repeated Sudanese words invites listeners into an oral ''join-in.'' Brown's vivid, full-page illustrations contribute to the overall feeling of authenticity, and their curving, linear motifs are reminiscent of African cave paintings. Thus this unusual and absorbing book offers an original ethnic experience.

Cats vs. dogs is the somewhat too familiar theme of ''Mean Murgatroyd and the Ten Cats'' - humorously involving a young girl, Arabella, the owner of 10 cats.

Refusing to be intimidated by the mean-eyed, big-jowled dog next door, Arabella thinks of a most novel solution to combat the dog's noisy pestilence: She turns into a lion! Lively, cartoonlike drawings contribute much of the humor , and children aged 3 to 7 will undoubtedly respond laughingly to the many looks of high-tension, hair-standing-on-end wariness of Arabella's cats.

Trouble is, the solution to Arabella's dilemma (not being able to find a real lion anywhere in town) is curiously contrived and uninteresting. Finding and wearing a lion's suit is certainly the next best thing to reaching her original goal - but it seems as though the character is more satisfied with it than the reader! When the answer lies too much in what to do about a problem, more than in a courageous confrontation with the problem itself, the rewards of victory don't go so deep.

Still, if it's a frenetic cartoon you want, that's what you'll get. And the story does go to show that a house cat's bigger, ancient ancestor is something every kitty can take heart in, if he or she lives next door to a growling bruiser!