80 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Remarks: This species finds its closest affinities with Collodes 

 tumidus, with which it shares the nongranulate carapace and bifid 

 rostrum. However, it is much larger than any specimen of C. tumidus 

 to come to our attention, being in fact larger than the largest C. 

 tenuirostris from the Gulf of California. Of greater importance, it 

 lacks several of the diagnostic characters of C. tumidus, notably the 

 inner branchial tubercles which, with the gastric and cardiac tubercles 

 (not spines), form a diamond on the dorsum of that species. With 

 respect to the erect gastric and cardiac spines it resembles C. granosus, 

 an extremely granulate species. The large postorbital spine with its 

 convex-concave anterior margin and the smooth basal antennal article 

 with its entire margins appear to this writer to justify the erection of a 

 new species on these salient characters, although it would be preferable, 

 for the sake of the pleopod, if a male were available to serve as the 

 holotype. 



The proposed new species is named for Elinor D. Robson, by whose 

 students at Ancon High School, Canal Zone, it was collected. 



According to James Zetek, resident manager, Canal Zone Biological 

 Area, the name "Venado" applies equally to Venado Beach and to the 

 offshore island with which it is connected at extreme low tide. Both lie 

 inside the Canal Zone western boundary, immediately east of the Pana- 

 manian village of Camaron. 



Genus PARADASYGYIUS, new genus 



Type: Microrhynchus depressus Bell. 



Description: Carapace depressed, tuberculate. Rostrum short, simple. 

 Postorbital spine large, curving around eye, separated by a slight inter- 

 ruption from inner orbital margin. Eyes large, flattened, retractile. Basal 

 antennal article with an external tooth visible at sides of rostrum, inner 

 margin dentate or entire; antennal flagellum long, hairy. Merus of 

 external maxillipeds narrow at base, cordiform. Epimeral plates 

 prominent. Chelipeds short, merus curved, manus inflated in male, sub- 

 triangular to subglobular. Ambulatory legs of second and third pair 

 subequal in length and longer than those of fourth pair; first pair 

 noticeably shorter and conspicuously hairy; hairs adapted to collecting 

 and retaining particles of mud and detritus; meri horizontally com- 

 pressed ; dactyli long, slender, unarmed. Sternum a flattened disc except 

 for a round swelling at base of chelipeds and, in advance of this, a stout 

 spine between maxillipeds. 



