412 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



tion may vary. They could be counted in but 2 specimens in both of which 

 the number was 9. 



Although T. hamadai is from a related host in Japan, T. proctocolus 

 is more similar to T. coryphaenae. I have collected what I consider to be 

 T. coryphaenae from Coryphaena hippurus at Tortugas, Florida. On 

 the basis of this material the questions raised by Dollfus (1935) can be 

 answered by saying that no copulatory organ is present and the vitellaria 

 are tubular and continuous, thus confirming the location of the species 

 in the genus Tetrochetus. 



T. proctocolus and T. coryphaenae are almost identical. The most 

 pronounced difference is egg size. My material of T. coryphaenae has 

 constantly larger eggs (32 to 35 by 16 to 19 jx). Yamaguti records 26 to 

 33 by 16 to 19 ^i for T. coryphaenae. Except for a specimen having both 

 abnormally small and abnormally large eggs, T. proctocolus eggs were 

 consistently 22 to 25 by 14 to 15 /x. Another difference between the 2 

 species is a relatively somewhat larger oral sucker in T. coryphaenae. 

 Because of the usual lateral view of specimens the most available dimen- 

 sions to compare are the lengths (anterior-posterior) of these suckers. 

 The following proportions represent in hundredths of millimeters these 

 ratios (oral sucker above acetabulum) : 



16 17 23 24 24 

 T. proctocolus 27 30 47 JS 39' 



18 27 28 36 36 37 20 (Yamaguti's 



1 . coryphaenae -^^ ^^ -t::^ -7-. -r^ -r, — 7^ , s 



25 39 36 44 46 42 29 record) 



T. coryphaenae seems to have thicker vitelline tubes with fewer coils 

 between anterior testis and acetabulum. The anterior extent of the uterus 

 and vitellaria is probably too variable to separate the two species. T. cory- 

 phaenae is from the intestine of its host rather than from the rectum. 



T. proctocolus is distinctly different from T. raynerius in sucker ratio 

 and location of the gonads. It differs from T. ha?nadai in sucker ratio, in 

 shape of pharynx, and in more posterior extent of vitellaria. 



A single specimen of Tetrochetus from the intestine of Trachinotus 

 rhodopus at Chatham Island is probably T. proctocolus. The sucker ratio 

 would so indicate, as well as most of the eggs, but a very few eggs were 

 abnormally large as compared with others. Another single specimen, prob- 

 ably T. proctocolus, was collected from the intestine of an angelfish 

 (Angelichthys sp.) from the Galapagos. In this specimen, a peculiar 

 abnormality was the entire absence of egg shells. The uterus was fully 

 developed and filled with naked embryos. The vitellaria were normal. 



