i9°5 ] 



ORTMAXN — AFFINITIES OF CAMBARUS. 99 



of his C. digueti, which show, on the one hand, that C. carinaius 

 Fax. is a synonym of this species, and on the other hand, that the 

 sexual organs have a rather peculiar shape. The figures of these 

 organs, given by Faxon (/V. U. S. Mus., 20, 1898, pi. 65, f. 2 

 and 3) are absolutely correct, but the description (p. 648) is rather 

 short and unsatisfactory. Faxon says: "Inner and outer parts 

 ending in a small horny tooth, anterior margin furnished with a 

 small tooth near the tip." Fig. 2 represents this organ of the 

 right side, seen from the outside : the outer part ends bluntly, 

 without a distinct tooth, while the inner part ends in a rather 

 pointed tooth, outside of which is a sharp spine that is longer than 

 the outer part. Faxon's Fig. 3 represents the identical part seen 

 from the inside : only the two tips of the inner part are seen here, 

 and the tip of the outer part is hidden behind the end of the inner ; 

 the inner part is flattened and hairy on the inside, and the " shoul- 

 der " ( " small tooth near tip " ) is distinctly developed. My male 

 specimen of C. digueti 'agrees in every detail with the figures of Faxon. 



A very similar structure is seen in C. cubensis (Faxon, 1885, pi. 

 7, f. 5), only here the flattened face of the inside is dilated, and 

 the shoulder is more prominent. In both cases, there are practi- 

 cally three tips to this appendage, two of which belong to the 

 inner part. 



The description of this organ in C. mexicanus (Faxon, /. c, p. 

 50) agrees closely, but possibly the "small, procurved spine" at- 

 tributed to the external part belongs to the internal, and then there 

 would be complete agreement. 



The double tip to the inner part, and the shoulder, which has a 

 very peculiar position, possibly give to these three species a more 

 isolated position within this subgenus, and might possibly justify 

 the creation of a separate subgenus, which then should stand at the 

 head of the genus. This would also agree well with the geographi- 

 cal distribution. 



Aside from these more primitive species (C. digueti, cubensis, 

 mexicanus), the first section contains two others (C. simulans and 

 gal Unas), which mark the transition to the third section, from 

 which they differ only by the number of hooks of the male ; the 

 third section contains more advanced forms of the simulans '-type. 

 The second section is a peculiar side branch going off from the first 

 section, which has acquired burrowing habits; this is known posi- 



