130 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. S4 



extremity of the piece the surface is expanded forward mesially; 

 basal structures of the gonopods resembling those of 'protenta^ to a 

 certain extent (fig. 16, e). 



Males with a ventral comb of hairs on the first three pairs of legs, 

 as in the other species, but none of the ensuing legs have ventral pads. 

 Females with ventral combs on the first two pairs of legs. 



Tijpe.—M?i\Q, U.S.N.M. no. 1247. 



Re'marks. — Two males and three females were collected beneath 

 rocks at the base of the cliffs in Cave Creek Canyon, Chiricahua 

 Mountains, Cochise County, Ariz., May 25, 1928, by E. H. Peebles 

 and H. F. Loomis. 



COLACTIS UTORUM (Chamberlin) 



Spirostrephon utorum Chambeelin, Pan-Pac. Eut., vol. 2, no. 2, pp. 61-62, 1925. 



In the original description of this species the remarks pertaining to 

 the dorsal crests apply to nearly all the western members of the 

 family that have been seen. Also some of the newly described 

 species are light in color, so that this character is of incidental im- 

 portance. The shape of the poriferous keels is the only character 

 that may be of generic value and would indicate relationship with 

 Colactis or He/ptium^ as does the number of segments. On the basis 

 of the distribution of these genera it is probable that the species 

 belongs in the genus Colactis^ and no doubt it is different from any 

 of the species described in this paper, although no characters are 

 given that may be used to distinguish it. 



HEPTIUM, new genus 



Type. — Heptiwn caHnellutn^ a new species from southern Cali- 

 fornia. 



Description. — This genus is closely related to Colactis^ but differ- 

 ences are mentioned in the following paragraphs. 



Transition to the full number of dorsal crests occurs on segment 

 18 or 19, instead of segment 16 or 17, as in Colactis. 



The outer basal portion of the male gonopods consists of a single 

 large piece instead of two or three distinct pieces, which, when 

 taken together, do not closely resemble the outline of the structure 

 in Heptium., although a relationship is evident. 



Males with seventh legs greatly reduced in size, not extending be- 

 yond the end of the fourth joint of the normal sixth pair of legs; 

 basal joint with a long, slender, erect spine developed from the 

 inner anterior angle and extending nearly as high as the apex of 

 the gonopods; joint 2 very short; joint 3 much longer, equaling or 

 -exceeding in length the combined remaining joints. One male of 



