i882.] 



Zoology. 



and I take the opportunity so offered of putting my observations 

 upon record, so as to facilitate future studies by others. 



Graff says the capsules observed by him in material supplied 

 from the Frankfurt a. M. Aquarium, by Dr. Schmidt, measured 

 about three millimeters long by one and a half wide, which 

 would correspond pretty nearly with the outline of the largest 

 capsule observed by me and represented in Fig. 9. But accord- 

 ing to him these large capsules contained from two to nine em- 

 bryos, while those observed by me never contained more than 

 one, the presumption, therefore, is, that they belong to distinct 

 species, and that on this specimen of Limulus, Planaria limit li was 

 not present. 



All of the capsules were apparently chitinous, and attached by 

 a cylindrical stalk to the surface of the branchial leaflets by a 

 l of the end of the stalk, as represented in 



Figs. 1-7 and 9. In form the capsules are oval and flattened, 

 lying down flat against the surface of the branchial leaflets with 

 the plane side. The lower side of the capsule is flat, the upper 

 convex, as shown in a side view, Fig. 4. When the young escape 

 they find their way out by the free end of the capsule, which is 

 ruptured as represented in Fig. 7. They are scattered all over 

 the branchial leaflets and on both sides of them. The different 

 sizes were often. seen side by side on the same leaflets together 

 with the parent worms, which, as Graff observes, had often eaten 

 through the branchial structures. So extensive was this damage 

 that I suspect they cannot bo considered merely as commensals, 

 but rather as true parasites, for it was frequently observed that 

 four or five successive leaflets were eaten through in the vicinity 

 of a large adult worm, so as to produce large irregular perfora- 

 tions with evidences of degeneration of the branchial tissues at 

 the margins of the openings. That they should find it easy to 

 feed off of their host is not to be wondered at, in that the branchial 

 leaflets are composed of two verv thin chitinous lamellae which 

 are kept apart by numerous rounded pillars; in the space be- 

 tween the lamellae and around the supporting pillars the blood of 

 the host circulates. In consequence of this arrangement, -" f * 





