TAPE-WOIMIS OF THE SUC-FAMEfA' AVITEMJNIXJ:. 339 



it becomes necessary to review their position, and to see liow 

 far they are related to Thy sanosoma. 



The points common to the three genera Stilesia, Avitel- 

 lina and Thy sanosoma are: the maro-inal arrangement of 

 the testicles, the irregular alternation of the single g'enital 

 pores (which does not hold good for Thysanosoma, double- 

 pored specimens being frequently met with in South Africa) 

 and the possession of a paruterine organ. They differ, how- 

 ever, in several very important points: Avitellina and 

 Stilesia do not possess either a shell-gland or a vitelline 

 gland ; their eggs receive nourishment from nutritive cells in 

 the ovarium and in the uterus. 



The points in which the three genera agree are hardly of 

 sufficient importance to weigh very heavily; the position of 

 the testicles and of the genital pores is liable to vary con- 

 siderably within a sub-family ; the possession of a paruterine 

 organ can, as shown by Fuhrmann (1908), be acquired 

 independently by genera belonging to various sub-families. 



The lack of a vitellogene gland and shell-gland and the 

 results of their absence are, however, quite sufficient to 

 separate the two genera from all other known cestodes. I 

 therefore propose to separate the genera Stilesia and 

 Avitellina from the Thy sanosomin je and to place them 

 in a new sub-family ol the Anopl ocephalidge, calling the 

 new sub-family AviteUiniiue, after the genus Avitellina, 

 which is certainly the better known of the two genera. 



Diagnosis of the A vitellininas. — Scolex without hooks 

 with four suckers. Segments short, genital pores irregularly 

 alternating, testicles in two or four groups, marginal, none in 

 the middle field. A single ovarium, no vitelline gland, 

 no shell gland; uterus single or double, eggs finally 

 enclosed in a paruterine organ. Eggs in ovary and uterus 

 surrounded (and nourished) by nutritive cells. Oncosphaere 

 with two envelopes. Type g'enus, Avitellina, Goug'h, 1910. 

 All the known species inhabit Ruminants, development 

 unknown. 



