269] PROTEOCEPHALIDAE—LA RUE 269 



anteriorly elongated to form a conical elevation, unarmed and not very- 

 prominent, distinct from neck. Breadth of head perhaps 0.35 mm. 

 Suckers four, fairly prominent, oval in shape, about 0.15 mm. long, 

 situated at four angles of head. No fifth sucker. Neck very long, nar- 

 row. First proglottids short, middle ones almost rectangular, posterior 

 and last ones decidedly rectangular, swollen in the middle. Ripe pro- 

 glottids about 1.80-2.0 mm. broad by 0.68-1.0 mm. long by about 0.34 

 mm. thick. Proglottids attached by full width. Intersegmental furrows 

 shallow. Corners of proglottids not marked. Segmentation indistinct. 



Genital organs as in genus. Genital pore marginal, irregularly 

 alternating in first one-fourth or one-fifth of proglottid length. No geni- 

 tal papilla. Testes spheroidal, 0.05-0.085 mm. in maximum dimension, 

 numerous, 100 or more, situated in single dorsal field outside of inner 

 longitudinal muscle sheath. Vas deferens a mass of coils inside the inner 

 muscle sheath. Cirrus-pouch 0.286-0.315 mm. long by 0.094-0.105 mm. 

 broad. Length of cirrus-pouch 5 to 6 to 6y 2 times into proglottid 

 breadth. Ductus ejaculatorius describing numerous coils. Cirrus slen- 

 der, unarmed. Vagina and vaginal opening always anterior to cirrus- 

 pouch. Vagina never crossing latter. Sphincter vaginae and receptacu- 

 lum seminis present. Vagina within inner muscle sheath. Vitellaria 

 lateral, extensive, ventral, follicles forming a single layer in cortical 

 parenchyma. Ovary posterior, bilobed, augmented by large protuber- 

 ances, projecting dorsally, partially outside of inner muscle sheath. 

 Organs of interovarial space as in Proteocephalidae. Uterus with many 

 long slender lateral outpocketings, ventral, and outside of inner muscle- 

 sheath. Egg-membranes not observed. Embryos 0.015-0.017 mm. in 

 diameter. 



Habitat : Intestine of Silurus sp., locality not stated. 

 Type : Slides in collection of Monticelli, from specimen No. 571 in 

 the Zoological Museum at Vienna. 



This species was first described from Silurus sp. by Monticelli 

 (1891:151-174). For this and nineteen other species of cestodes from 

 fish he proposed the genus Tetracotylus, without, however, naming a 

 type species. That genus was based on Taenia coryphicephala, the spe- 

 cies which he described most completely. Lonnberg (1894:803) listed 

 this as one of the species of Ichthyotaenia without entering into a dis- 

 cussion of its anatomy. Riggenbach (1896:267) listed this among the 

 species of Ichthyotaenia. Braun (1894-1900:1680-1681) states that Mon- 

 ticelli 's genus Tetracotylus is based on the species Taenia coryphicephala 

 but that the generic name suggested by Monticelli is a homonym of the 

 name Tetracotyle suggested by Filippi (1854). He said moreover that 



