PART 1 GARTH : PACIFIC OXYRHYNCHA 63 



Color in life: Pale gray. (Crane) 



Habitat: Analysis of the bottom types from which Euprognatha 

 bifida was dredged shows a primary breakdown into sand 58 per cent, 

 mud 20 per cent, coral and coralline 14 per cent, and rock 8 per cent. 

 A secondary breakdown of the sand bottoms shows shell present 22 

 per cent of the time. Mud and rock were accompanied by sand more 

 frequently than not. This compares well with Crane (1937, p. 55), 

 who reported it usually on sandy bottoms, or on bottoms of sand and 

 crushed shell. 



Depth: Hancock expeditions specimens were obtained in from 1 to 

 90 fathoms. All 14 occurrences in depths of over 50 fathoms were in 

 the Gulf of California or at Clarion Island. 



Size and sex: Only the 1949 Velero IV cruise material has been 

 subjected to measurement, and among these none was found as long as 

 the 15.3 mm male recorded by Rathbun (1925). Males range in size 

 from 2.8 mm to 9.6 mm, females from 4.8 mm to 9.1 mm, the smallest 

 as well as the largest being ovigerous. 



Breeding: Females with ova have been taken off Lower California 

 from March through May, in the Gulf of California from January 

 through April, off Mexico south of Cape Corrientes in March and in 

 May, off Costa Rica and Panama in February, and off Colombia in 

 January. 19 of 21 female specimens from one Costa Rican station were 

 ovigerous. 



Remarks: While visiting the U. S. National Museum in 1940 the 

 writer compared Hancock expeditions specimens from Velero III sta- 

 tion 699-37, Gulf of California, with the holotype male of Euprognatha 

 bifida (U.S.N.M. No. 17335) and with the photographed specimen of 

 Batrachonotus nicholsi (U.S.N.M. No. 21869), a female. (The types 

 of the latter species, also females (U.S.N.M. No. 18107), are small, 

 dry specimens, and do not lend themselves well to study.) The photo- 

 graphed specimen was found to be a spine-for-spine duplicate of the holo- 

 type of E. bifida, while the types of Batrachonotus nicholsi are believed 

 to represent merely a tuberculate form of Euprognatha bifida which 

 occurs frequently in female and young male specimens. In this form 

 the tubercles of the carapace are larger and more beadlike, fewer in 

 number, and disposed on the elevations only, the intervening sulci being 

 smooth and bare. The cardiac prominence resembles a berry. The paired 

 intestinal spines are reduced to bead granules, as are most of the other 

 carapace spines, including the gastric, branchial, and supraorbital. Of 

 the remaining series of specimens referred by Rathbun (1925, p. 128) 



