REPORT ON THE PHYLLOCARIDA. 19 



Tlie internal organs I have not succeeded in isolating by dissection, owing to the 

 small size of this form. In the previously mentioned specimen, rendered pellucid by 

 preparation in Canada balsam, and represented on PI. I. fig. 1 , the intestine can, however, 

 be easily traced running through the axis of the body and terminating in a strongly 

 muscular rectum, which traverses the last caudal segment (see also PL II. fig. 10). At 

 the sides of the intestine the ovaries (PI. I. fig. 1, Ov) appear very distinctly, owing to 

 their being rather more opaque than the surrounding parts. They have the form of 

 two very elongate and narrow tubes running through the whole trunk and pleon, and, 

 moreover, projecting anteriorly to some extent within the cephalic part and posteriorly 

 almost reaching to the end of the second segment of the tail. They were each filled by 

 only a single series of ovarial ova, each with a very distinct germinal vesicle in the 

 centre. 



The musculature of the body may also be rather distinctly traced in the specimen. 

 Thus, in the cephalic part several strong muscular bundles are seen passing from the 

 dorsal side to the several appendages belonging to that division, and in the succeeding 

 part of the body, besides the muscles moving the respective limbs, there is another 

 group of very powerful muscles running parallel to the axis, and by the aid of which the 

 body admits of being moved in relation to the cephalic part or to the carapace, as does 

 also the tail upon the pleon. Of these muscles the dorsal, or extensores, are the more 

 numerous, passing from the one segment to the other and apparently forming several 

 layers, whereas the ventral musculature is chiefly restricted to two strong muscles 

 running backwards beneath the intestine, and in the tail dividing into separate bundles 

 for each segment. The heart, distinctly visible in living animals from its rapid 

 pulsations, cmite escapes attention in dead specimens owing to its very thin and pellucid 

 walls, and the nervous system, as also the cseca of the intestine are very difficult to see 

 even in fresh specimens. That all these parts on the whole may agree with those in 

 Nebalia, I cannot but believe, as these two genera are otherwise very nearly related. 



Development. — As above stated, some of the specimens in the collection were 

 laden with eggs and embryos. On PL II. figs. 11, 12, I have represented one of the 

 embryonic stages in a ventral and lateral aspect, having found it somewhat different from 

 the corresponding stage of Nebalia, as figured by Metschnikoff. The length of this 

 embryo is nearly 1 mm. As may be seen, it is still provided with the so-called larval 

 cuticle, forming a pellucid homogeneous sheath investing the greater part of the body, 

 and terminating in a slightly bilobed extremity. The anterior part of the body, 

 constituting the cephalic division, is very considerably dilated, almost globular, and to 

 a great extent filled up with the remainder of the yolk, whereas the succeeding part 

 gradually tapers posteriorly. The latter does not exhibit any trace of the strong dorsal 

 curvature found in the corresponding stage of Nebalia, according to the statement of 

 Metschnikoff, but is cmite straight, or with the terminal part even slightly curved 



