e. 0. Whitman 



where of equal breadth ; sometimes its anterior portion is very broad 

 compared witli the posterior part, whieh is slender and mudi elongated, 

 resembling tlien a tadpole ; and , again , the body is , so to speak , con- 

 tracted, comparatively short and thick.« 6, p. 202. The number of 

 the polar cells (»plaques«) was not ascertained, and hence its g-eneric 

 Position remains problematic. The various forms of the body give some 

 ground for thinking that this species is distinct from I). Eledones, while 

 the form of the calotte excludes it from the genus Dicyema , and makes 

 it probable that it has been correctly placed in the genus Dicyemennea. 



10. Dicyemennea gracile Wag. Figs. 48 — 50, PI. 4. 



Found o\\\y \u Sejìia officinalis^ always in company 

 with D. tr uncatum. Calotte enneamerous, globose, or- 

 thotropal, wider than the body and well marked off. 



The polar cells agree in number and disposition 

 with D. Eledones. The propolars always much smaller 

 than the metapolar s. 



The head for med exclusively by the polar cells. 



The 2 lateral parapolars scarcely differ in thick- 

 ness and general appearance from the ectodermal cells 

 of the trunk. 



Ectodermal cells, thin, their number and arrange- 

 ment the same as in D. Eledones. 

 No verruciform cells. 

 Length 4 — 6 mm. 



This species has been found in every S. officinalis that I bave 

 examined, but much less abundant than the companion species. It is 

 generally distributed in colonies in the manner described under B.mos- 

 chatum. 



The wide diifereuce in form and aspect betweeu this species and 

 D. truncatum^ with which it is associated, is made apparent by figs. 48 

 and 53 , PI. 4 ; and the equally conspicuous differences in the form and 

 composition of the calottes may he seen by comparing figs. 49^ — 50 with 

 54—59. 



The differences between this Dicyemid and D. Eledones are of 

 such a superficial nature that I cannot regard them as conclusive evi- 

 dence that the two forms are speci fically distinct ; stili they are suffi- 

 ciently obvious and general to justify a provisionai Separation. 



