A Contribut. to the Embryol., Life-history, aud Classificat. of the Dicyemids. 23 



with D. truncatum of aS*. officinalis. Before tliese diflferences could be 

 accepted as conclusive evidence of a new species , it was necessary to 

 know if they were Constant. Further examinations proved the contrary. 

 In the second case recorded, the difference in the granulation of the 

 ectoderm was absent ; and the calotte, if a little largerthan the a verage 

 in D. truncatum of S. officinalis^ agreed so nearly in this respect and 

 so perfectly in every other particnlar , that I felt compelled to abandon 

 the idea of attaching a specific vaine to these distinctions. 



Dr. FoETTiNGER (29), in a recent paper on some new Infusoria, 

 found in the renai organ and the liver of certainCephalopods, incident- 

 ally remarks that the Dicyema of Sepia elegans is a new species, 

 which he proposes todescribe in a future communication. I bave exam- 

 ined five S. elegans , and bave found Dicyema in every case ; and I 

 bave failed to detect any Constant difference between them and B. 

 truncatum of ä officinalis. The differences which I bave noted in indi- 

 viduai cases bave not proved to be Constant , nor bave they been eitber 

 greater or more numerous than those observed in specimens obtained 

 from diflferent S. officinales. The chief difference noted concerned the 

 caudal cells , which were prevailingly small and otherwise not so well 

 characterized as they gen e ra 11 y are in individuai from the Cuttle-fish. 

 But as a considerable number of individuals did not differ at ali in this 

 respect from the average form met with in the last named Cephalopod, 

 the difference can not be regarded as anything more than a tendency to 

 Variation induced by the somewhat unlike conditions of life oifered by 

 the two dififerent hosts. 



6. Dicyema Schulzianum E. V. Ben. 



Found in Sepia biserialis Den. de Mont. 



Unfortunately I bave not met with individuals of this 

 species sufficiently numerous and well preserved to admit 

 of accurate analysis, and bave therefore but little to add to the 

 very brief account given by Van Beneden. His statements 

 are, that the parapolars take part in the formation of the head, 

 as in D. truncatum] the calotte is larger than that of D. trun- 

 catum, forming a large part of the cephalic enlargement 

 in adults, and the whole of this enlargement in the young; 

 the metapolars are quite different from the propolars. Noth- 

 ing is said in regard to the number of cells in the calotte, 

 or the total number of ectodermal cells. I am quite certain 



