92 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 118 
Family Rhachodesmidae 
In the present collection are two vials labeled “1923, Haiti?, O. F. 
Cook,”’ containing a female Chondrodesmus species and two species 
of rhachodesmids, one representing a new genus. The fact that no 
rhachodesmids or species of Chondrodesmus are known from Haiti 
was called to Dr. Cook’s attention, and he sent me this note: ‘Col- 
lections also had been made in the Canal Zone that year and it seems 
probable that the material was from there.” Species of Chondro- 
desmus but no rhachodesmids have been reported from Panama, 
although they are known from adjacent regions. Still it seems rea- 
sonable to accept Dr. Cook’s explanation and describe the new forms 
as likely members of the Panamanian fauna. 
Genus Aceratophallus Carl 
Aceratophallus Carl, Rev. Suisse Zool., vol. 10, p. 608, 1902. 
Aceratophallus quadratus, new species 
FiacurREs 2j, 3a—b 
Hototyre: Male, USNM myriapod collection 2639, presumably 
from Canal Zone (see paragraph above), 1923, O. F. Cook. 
AuuotyPE: Female, USNM, collection data same as for holotype. 
Paratypes: Male, Snow Museum, male and female, author’s col- 
lection, collection data same as for holotype. 
Draenosis: Closely related to A. lamellifer Brolemann as indicated 
by the gonopods, which show obvious differences; also the body is 
shorter and relatively broader. 
Description: Largest male 26 mm. long, 4 mm. wide; largest 
female 31 mm. long, 5 mm. wide; original color bleached out. 
Body parallel sided, compact, little of prozonites showing; dorsum 
of male nearly flat, female more convex; lateral keels nearly horizontal, 
wide, projecting squarely outward with ectal margin nearly straight, 
giving segments a strikingly rectangular appearance. Head com- 
pletely beset with variable length setae, those at back of vertex 
shortest; vertex with deep median furrow; antennae slender, joint 2 
longest, followed by subequal joints 3 and 6. 
Segment 1 sublunate, over three times as broad as long; anterior 
margin with raised rim behind which are six erect setae; surface 
coriaceous or smooth at middle but granular on sides; posterior 
border conspicuously emarginate across middle. 
Beginning with segment 2 both corners of keels are almost acutely 
squared, the anterior corner with a sharp tooth present to segment 18; 
from middle of body backward anterior corners slightly rounded, 
