NO. 14 manter: digenetic trematodes of fishes 379 



Excretory pore terminal; excretory vesicle extending dorsal to hind 

 testis, then ventral to anterior testis to end at level of ovary. A pair of an- 

 terior tubules on each side extends to anterior end of body and a pair of 

 posterior tubules extends to near posterior end of body. No lymphatic 

 vessels seen. 



GENERIC DIAGNOSIS OF MYZOTUS 



Anallocreadiinae. Body robust, cuticula thick, smooth, with tw^o con- 

 spicuous bilobed flaps, one on each side of acetabulum. Gonads tandem, 

 unlobed. Cirrus and cirrus sac lacking; genital sinus long; seminal vesi- 

 cle simple, tubular, uncoiled. Mehlis' gland, Laurer's canal, and seminal 

 receptacle large; vitellaria extensive. Lymph vessels lacking. Type spe- 

 cies : M. vitellosus. 



Discussion. This allocreadid genus can be referred to the Anallocrea- 

 diinae because of its lack of cirrus and cirrus sac and its possession of a 

 tubular genital sinus. It is, however, very different from other genera not 

 only in its peculiar acetabular lobes but in its smooth cuticula, thick body, 

 and extensive vitellaria. Crassicutis Manter, 1936 with its practically 

 smooth skin is perhaps a related genus, but its general appearance is very 

 different, its body flattened and wide, its gonads of different location, its 

 ceca narrow, and its acetabulum unmodified. The muscular modification 

 of the acetabular lips of Myzotus is suggestive of Myzoxenus Manter, 

 1934 (see p. 299), but Mj'zoxenus lacks a genital sinus, has a cirrus sac, 

 and is without acetabular flaps. Mj^zotus shows considerable resemblance 

 to Apocreadium Manter, 1937 and Choanodera Manter (see p. 345), 

 notably in the terminal genital tubes which are practically identical, in the 

 histology of the ootype region with its huge Mehlis' gland and large Lau- 

 rer's canal, and in its excretory system. Furthermore, Choanodera does 

 possess ventral body folds which, however, involve the entire forebody. 

 The similarity to Choanodera was so pronounced, especially in the repro- 

 ductive systems, that one could expect to discover lymph vessels in Myzo- 

 tus. Careful search reveals no trace of such vessels. Thus again it is indi- 

 cated (see p. 348) that lymph vessels may be present or absent in related 

 genera. In this paper, Myzotus is considered in the subfamily Anallocrea- 

 diinae. 



The name Myzotus is from myzo (= sucker) and otus (= ear) and 

 refers to the earlike flaps of the acetabulum. The name vitellosus refers to 

 the extensive vitellaria. 



