CROSSOBOTHRIUM LACINIATUM AND DEVELOP- 

 MENTAL STIMULI IN THE CESTODA. 



W. C. CURTIS. 



In the spiral valve of the "sand shark" (Carcharias littoralis) 

 taken from the Woods Roll region there is found in a large 

 majority of the specimens examined the Cestode, Crossobotlirinin 

 laciniatinn. This genus and species was first described by Linton 

 (" Rept. U. S. F. Com." for 1886), and in subsequent papers 

 appearing in the same publication or in the " U. S. F. C. Bul- 

 letin," he has added further important notes, the whole making 

 an accurate and satisfactory systematic description. 



A striking feature of the species is the remarkable clearness 

 with which the important features of Cestode structure can be 

 demonstrated. The water vascular system, main trunks and 

 flame-cells can be seen in the fresh specimen with the greatest 

 ease. Almost every detail of the complicated reproductive or- 

 gans is seen in well-stained whole mounts of the motile proglot- 

 tids and much of this in specimens freshly prepared. The mode 

 of using the suckers on the head, the activities of the motile pro- 

 glottids and their mode of egg-laying and the development of 

 these eggs in sea-water as far as the six-hooked embryo are all 

 easily demonstrated. Moreover, there occurs in the cystic duct 

 of the squeteague (Cynoscion rcgalis], a not uncommon food of 

 the "sand shark," a tetrabothrian larva which, if not the larva of 

 Crassobothrium laciniatum, probably belongs to some very closely 

 related form. This larva, which was first described and figured 

 by Linton ("Rept. U. S. F. Com.," 1886), is again an extremely 

 favorable object for study. 



If it is possible to obtain conclusive evidence that this tetra- 

 bothrian larva of the squeteague is indeed the larva of C. lacin- 

 iatum, we shall have but one gap in the life history of this species, 

 viz., the transfer to the squeteague of the six-hooked embryo 

 which develops in the open ocean. 



Such favorable material it seemed to me might present, upon 

 careful examination, facts which would be suggestive along the 



I2 5 



