With one possible exception no crustaceans were found depicted in the Maya codices, but we have introduced figures of two from the Nuttall Codex. The first of these (Pl. 4, fig. 5) is probably a crayfish, perhaps _Cambarus montezumae_. It seems unlikely that the so-called Spanish lobster (_Palinurus_) can be intended or the powerful spined antennae would have been shown. It is interesting to note that the stalked eyes are clearly pictured. The second example seems to be a crab (Pl. 4, fig. 6). Two large chelae of nearly equal size are simply drawn and four rounded projections at the top of the figure appear to represent the walking legs. Its rotund form and subequal chelae suggest the land crab, _Geocarcinus_, but exact determination is of course impossible. What is certainly a large crab, perhaps of the same species, is shown in Tro-Cortesianus 88c (Pl. 36, fig. 1) in connection with a dog whose feet it seems about to pinch with its two large chelae. The shell is ornamented in a conventionalized way as if with scales. ARACHNIDA In Codex Borbonicus 9 (Pl. 4, fig. 4) there is represented a stout-bodied form of spider with two sharply pointed chelicerae projecting from the conventionalized mouth. These characteristics together with the absence of any web, suggest a large predacious species, probably the tarantula (_Tarantula_ sp.) which is common in Mexico. The acute powers of observation shown by the artist are evinced in this figure since he draws the spider correctly with eight legs instead of the six or ten sometimes seen in drawings by our own illustrators. ARACHNOIDEA