McCrady.] 178 [Dec. 3, 



round ovoid, or ellipsoidal chambers. These chambers sometimes 

 exhibited what seemed to be a mere cavity, formed by an enlarge- 

 ment, as at a, of the central canal, sometimes to have this cavity 

 tilled with an opaque nucleus darker than the other parts, as at b. In 

 no case did I observe any contractility, such as would have been in- 

 volved by the formation of these narrowings and widenings of the 

 tube under the microscope. Indeed, the impression left upon me by 

 the distinct resistance of the tubes to the knife was that they would 

 probably prove chitinous. The species, therefore, is, in respect of the 

 rigidity of its tube, more in accord with the observations of Baer and 

 Siebold upon B. polymorphus, than with those of Lacaze-Duthiers 

 upon B. Haimeanus. Again, as at c, would sometimes be seen a 

 worm far advanced in development, and in the larger ellipsoidal cysts 

 were several still more advanced stages. I was, however, prevented 

 from continuing the observations; and this will account for the 

 meagreness of detail in the drawings marked 7 and 8, of which the 

 former represents a worm liberated by the breaking of the tubular 

 stems during removal. My journal records that the tentacula are 

 remarkably long and extensile, and that they appeared bristling along 

 their whole length with pointed cells, having a general resemblance 

 to lasso-cells, but that I could find no appearance of a lasso either 

 within or without these cells. I have' no recollection of a ventral 

 aperture or sucker, and my journal does not even allude to any fea- 

 ture of appearance which might be so interpreted. Of course I do 

 not consider this conclusive that there was none, and I have there- 

 fore abandoned the generic name (Hydricuculus) I had given to the 

 parasite, and have assigned it to the genus Bucephalus von Baer. 



Meagre as are these details and drawings, they appear to me to in- 

 dicate quite a distinct species from B. Haimeanus. The younger 

 stages show a proportion between the size of the budding tentacula 

 and that of the body, quite different from what appears in the draw- 

 ing's of Lacaze-Duthiers. These tentacular buds are much shorter 

 and stouter in proportion, and the body also stouter and shorter than 

 in B. Haimeanus. On the other hand, the advanced larva, fig. 7, 

 seems to be considerably narrower and longer than the other species, 

 and its tentacula shorter. This difference, however, may be due to 

 age. Though I observed fine transverse striations, the more distinct 

 constrictions of the animal's outline presented to me none of that 

 regularity indicated by Lacaze-Duthiers. They seemed to be mere 

 irregular contractions of the body wall at different points, no one of 



