NO. 14 MANTER : DIGENETIC TREMATODES OF FISHES 345 



maphroditic sacs. He considered them nearer the amphistomes than the 

 distomes and tentatively classified them in the family Opistholebetidae, 

 subfamily Megasoleninae. The same author (Manter, 1937) described 

 the genus Apocreadium which, while possessing lymphatic vessels, lacks 

 all trace of a cirrus sac and shows many similarities to the Anallocrea- 

 diinae. Ozaki (1937, 1937a) held that Gyliauchenidae (with lymphatic 

 vessels) could be separated from Opistholebetidae (without lymphatic 

 vessels). He then considered Petalocotyle in the Gyliauchenidae but did 

 not definitely allocate Megasolena or Hapladena to any family, although 

 implying relationship to Gyliauchenidae. Park (1938) complicated this 

 tendency toward amphistome relationship by describing the genus Caras- 

 sotrema, which has a hermaphroditic sac (and single testis) as does Hap- 

 ladena, but lacks lymphatic vessels. The single testis is not of more than 

 generic significance. Park's comparison to Deradena is based on an error 

 by Linton of confusing specimens of Hapladena with specimens of Haplo- 

 splanchnus, as explained by Manter (1937a). The genus Deradena is a 

 synonym of Hapladena, and most of the species described by Linton be- 

 long in the genus Haplosplanchnus. Carassotrema is indeed very similar 

 to Hapladena, differing only in lacking lymphatic vessels. The peculiar 

 hermaphroditic sac is so unique that there seems little doubt that Carasso- 

 trema is to be classified along with Hapladena in the subfamily Megaso- 

 leninae. Park's work thus indicates that the presence or absence of lym- 

 phatic vessels may not be of such great significance as to warrant the plac- 

 ing of the Megasoleninae among the amphistomes. Furthermore, there 

 appear to be lymphatic vessels in a species of Opechona and in a species of 

 Pseudolepidapedon described below. The writer's view (Manter, 1937) 

 that the Allocreadiidae show evident relationship to the Paramphisto- 

 midae is further supported by these recent findings. Sooner or later, more 

 information will determine the placing of the subfamilies and families in- 

 volved. For the present, the family Gyliauchenidae should probably be 

 considered in the superfamily Allocreadioidea. 



Choanodera caulolatili, new genus, new species 

 (Plate 33, fig. 18) 



Hosts: Caulolatilus anomalus (Cooper) (type host) 

 Caulolatilus sp. 



Location: Intestine 



Localities: Cerros Island, Mexico (type locality) 



James Island, Galapagos 

 Number: Many in each host 



