REPTILIAN TAPEWORMS. 261 



pore, and this thicker proximal region lies straight within the 

 sac. The cirrus is invested with a layer of glandular cells. This 

 layer is continuous with the subcuticular layer of the body. The 

 male orifice, as is general among the Ichthyotseniids, is some- 

 times in front of, and sometimes behind the vaginal pore. There 

 is nothing remarkable about the ovary or the vagina. 



§ Resume and General Observations. 



The foregoing account of the worm Solenotmnia viperis proves 

 the existence in a New World snake of an Ichthyotpeniid, most 

 nearly allied to my genus Ojjhidotcenia, which is Old World in 

 range, and at present known only from India, This distributional 

 fact gives at once a certain a priori reason for justifying the 

 distinctness of the two genera. I do not, however, attempt to 

 justify my conclusion by the geographical fact only. The large 

 size of the scolex, the pecular apical sucker, and the ventral 

 groove upon the mature segments seem to me to be sufficient 

 facts to go upon in the present state of our knowledge of the 

 Ichthyotseniidae. I cannot, however, state the absence of this 

 apical sucker in Opthidotcunia. The most valid reason is the 

 gaping of the uterine slit to form a ventral groove upon the 

 mature segments. In this respect Solenokenia has advanced a 

 stage further than OpMdotcenia. For while there are traces of 

 separate and pre-existing uterine pores, these are replaced by an 

 opening up (however caused) of a ventral median area of the 

 uterus and integument. This leads the way to — if it be not 

 identical with — the conditions recorded by Zschokke and others in 

 Calliohothrium and other genera. It appears to me that inas- 

 much as my specimens of Ophidotcenici were furnished with fully 

 mature proglottids (as regards ova and utei-i), a ventral slit is not 

 developed in that genus, and is therefore a legitimate character 

 in the definition of Solenotcenia. 



The existence of this ventral uterine slit still further justifies 

 the relationship between the Ichthyotaeniids and Calliohothrium, 

 and other " Bothriada3," and their removal from the Tetracotylea, 

 with which they have been placed, though sometimes only doubt- 

 fully. It seems probable that their definite inclusion by Max 

 Braun (in Bronn's ' Thierreichs ') with the Tetraphyllidea is 

 correct. 



