162 



shorter and more delicate in appearance than in the case 

 of Ph. Jactuca. In the median proglottides the irregular 

 alternating position of the penes on the margins of the 

 segments can usually be made out. 



The measurements of the specimen figured are : — 



Greatest diameter of head : 2'0 mm. ; 



Length of strobila : -^G mm. ; 



Greatest width of a proglottis : I'Ci mm. 



Pig. 17. Phyllobothrium thridax. Mag. 40 dia. 



Crossobothrium laciniatum, Linton.— Fig. is. 



Host : Raia hatis, oif-shore grounds. 



The genus Crossobothrium was founded by Linton* 

 for the reception of a species having the following 

 characters: "Body articulated, slender, flattened, sub- 

 quadrate ; neck short or none ; bothria four, opposite, 

 pedicelled, unarmed, each provided with one auxiliary 

 acetabulum on the anterior border; faces of the bothria 

 with a raised rim or border, which becomes more or less 



•'= Commissioner's Rept. U.S. Commission of Fish and Fish<'iiis. 

 part xiv., Washington, 1889, Pp. 470-4. PI, 3. tigs. 4-18, 



