ALLEN: FOSSIL MAMMALS FROM CUBA. 143 



that in a young skull of C. prehcnsilis having but three molariform 

 teeth, they are nearly as apparent, though the skull is already 

 somewhat produced behind, the orbit is only slightly higher than the 

 antorbital foramen, and the supraorbital ledge shows a distinct pro- 

 cess. The incisors are white in the young C. jjrchcnsiUs as in adult 

 C. nana, but in adults of both C. prehcnsilis and C. melamirus are 

 yellow. A distinctive feature of the palate in C. nana is the knife- 

 like median bony ridge, terminating in a slight projection at the 

 posterior border. The teeth are hardly to be distinguished- except 

 for their small size, from those of C. prehcnsilis. 



Except for the brief account by Chapman (1901, p. 320) no com- 

 parisons seem to have been made between C. prehcnsilis and C. 

 mclanurus. The series of both species in the Museum, shows that 

 the skulls of the two are very similar, and differ chiefly in that C. 

 mclanurus has slightly more inflated frontals, with less developed post- 

 orbital processes. On the inferior side of the skull, the noteworthy 

 difference lies in the narrower basioccipital and basisphenoid of the 

 latter species. So greatly does C. melamirus resemble C. jjrehensUis 

 in its general characters that it seems reasonable to consider it an 

 offshoot from the latter, that under the slightly different conditions at 

 the eastern end of Cuba, and with perhaps slightly more squirrel-like 

 habits, has developed here since the isolation of Cuba from the main- 

 land. The tail is apparently not used as a prehensile organ in the 

 way characteristic of C. prehcnsilis, for the hairs are longer and unworn 

 in the series studied, in coLtrast to the short-haired tails of C. prc- 

 hensilis in which the hair is often much more worn away on one side 

 than on the other. The color of the tail in C. vielauurus varies from 

 black to deep maroon or rusty. 



Correlated with the difference in use of the tail, is its greater bushi- 

 ness in C. mclanurus, as well as its tendency to break off easily near 

 the base, a peculiarity it shares with the Echimyinae. Dr. Barbour, 

 who is familiar with both C. prehcnsilis and C. mclanurus in life, says 

 that the hunters are always careful not to seize a wounded C. mclanurus 

 by the tail, well knowing how easily that member parts and allows the 

 animal to escape, whereas with C. prehensilis no such precaution is 

 taken. As with the spiny-rats, the place where the tail breaks easiest 

 is near the base, where the character of the hair changes sharply from 

 the shaggy pelage of the body to the shorter covering of the tail. The 

 loss of this appendage seems to cause no particular discomfort to the 

 animal. It comes away easily, without bleeding, leaving a rosette of 

 frayed muscle-fibers at the stump, just as with a lizard's tail when 

 broken. 



