NO. 14 MANTER : DIGENETIC TREMATODES OF FISHES 427 



Discussion. These specimens were all assigned to a single species in 

 spite of some differences noted in shape and size of the eggs. However, 

 all gradations between the short plump eggs and the narrow bowed eggs 

 could be found in different specimens (fig. 113). Sample measurements 

 (in ix) from different specimens including extremes are: 17 by 14, 19 by 

 12, 22 by 15, 23 by 13, 22 by 12, 24 by 14, 25 by 11, 25 by 12, 26 by 14, 

 26 by 13. In the absence of other constant or significant differences these 

 trematodes were considered a single species, L. microstomum. This species 

 is easily distingiu'shed from 2 other Lecithochirium species collected, viz., 

 L. magnaporum and L. muraenae. 



While my specimens are somewhat smaller than those described for 

 L. microstomum and the egg size somewhat larger, because of the varia- 

 tion in these characters the differences were not considered specific. The 

 details of the sinus sac, the bipartite prostatic vesicle, and the vitelline 

 lobes are as in L. microstonniin. The United States National Museum 

 kindly loaned the type and paratype specimens of L. microstomum. 

 Chandler ( 1935) states the egg size as 16 by 12 p., but this seems to vaiy 

 up to 19 by 10 to 12 /x. 



The question of sucker ratio does not help much in distinguishing 

 L. microstomum, L. synodi Manter, 1931, and my specimens. Chandler 

 gives 1 :2.5 to 1 :2.8 for L. microstomum and in the type specimen it is 

 1 :2.5. Over a dozen specimens of L. synodi show a ratio usually about 

 1 :1.33 but ranging from only about 1 :2 up to 1 :2.5. In other words, the 

 ratio in L. synodi ranges from 1 :2.5 somewhat downward, while in L. 

 microstomum it is 1 :2.5 to somewhat above. My Galapagos material is 

 more like L. synodi, the sucker ratio being usually about 1 :1.33, but it 

 may be fully 1 :2.5 or slightly above. Thus, all three species may meet at 

 a sucker ratio of 1 :2.5. L. magnaporum has a fairly distinctly smaller 

 ratio varying on either side of 1 :2, while L. japonicum is distinctly differ- 

 ent in its 1 :3 or 1 :4 ratio. L. exodicum is like L. microstomum in this 

 ratio. 



A restudy of specimens of L. synodi reveals an error in the description 

 in that a bipartite prostatic vesicle is present. It is, however, usually very 

 indistinct. The anterior portion is very small and cylindrical, usually 

 appearing rudimentary and sometimes appearing absent. The posterior 

 portion is larger and cylindrical but smaller than in L. microstomum. In 

 spite of the removal of these supposed differences between L. synodi and 

 L. microstomum, I believe that L. synodi is specifically distinct. It has a 

 sinus sac that is almost cylindrical and not enlarged at its base. Its ductus 



