PART 1 GARTH : PACIFIC OXYRHYNCHA 409 



Coming to specimens within the size range formerly assigned to 

 Stenocionops triangulata, a 30 mm female from the Gulf of California 

 has the required nine median spines, but some of them are reduced to 

 mere tubercles and the row of six spines trending diagonally inward 

 from the postbranchial lacks all but the first and last. A 22.5 mm female 

 and a 15.5 mm male from Port Culebra, Costa Rica, have seven and 

 five median spines, respectively, and the anterior of the three lateral 

 branchial spines makes its appearance as a small spine between the now 

 single hepatic and median branchial spine. An 11.5 mm female from 

 La Libertad, Ecuador, shows five median spines also; but a 5.6 mm 

 young from Cocos Island has no median branchial spines and only three 

 lateral spines. It is apparent that spines are added with age, that lateral 

 spines appear earlier than median, and that of the two hepatic and three 

 branchial spines of the adult, the anterior branchial and anterior hepatic 

 are later additions. 



The final question, that of following Boone (1938, p. 220) in 

 synonymizing both Stenocionops triangulata and S. macdonaldi to S. 

 ovata (Bell), has been approached by a careful review of Galapagos 

 Islands material previously referred to S. triangulata (Garth, 1946) 

 in the light of Hancock mainland material previously discussed, and of 

 such additional specimens as have become available for study. A detailed 

 comparison of the 40 mm Wenman Island male, referred with a question 

 mark to S. triangulata (Garth, 1946, pi. 67), with a 43 mm female from 

 Jicarita Island, Panama, shows no differences which might be considered 

 specific, although supernumerary spines are present on all areas in the 

 Galapagos specimen. The retention of the name S. ovata for a postulated 

 Galapagos endemic species having exactly eight median and four or five 

 lateral spines becomes academic in view of the demonstrated acquisition 

 of median and lateral spines with age in mainland specimens. The diffi- 

 culty of reconciling the external maxilliped with Bell's illustration can 

 be met only by allowing the artist the liberties which he is known to 

 have taken in other instances. 



Stenocionops beebei Glassell 

 Plate Y, Fig. 3 ; Plate 45, Fig. 2 



Stenocionops beebei Glassell, 1936, p. 214. Crane, 1937, p. 61, pi. 4, 

 figs. 13-15. 



Type: Female holotype, N.Y.Z.S. No. 36,714, length 56 mm, width 

 including spines 45 mm, without spines 38 mm. 



