MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES. 347 



F. j\faxtitj(>i>n.i xtage. After it had been kept three days this larva passed through -a nionlt, 

 by which only slight changes were introduced. The fourth pair of walking legs is now distinctly 

 jointed, the fifth remaining as a bud. The llagellum (endopodite) of the second pair of antenna? 

 uncoils and speedily lengthens. The terga of the first and second abdominal somites bear on the 

 lower lateral margins of each side a short tooth. The larva lived four days without further ecdysis. 

 Figs. 20, 27, 30, and .>1 are from this stage. 



G. MfiKtif/opiix stage [PL xi, Figs. 28, 29, 32-34, PI. xnj, (Length = 9"""). An older larva, 

 caught in the net on May 7, is shown on PI. xn. The most striking features of this form are the 

 long trailing antenna? (tlagella of the outer pair), the actual length of which is about 1 inch, which 

 is more than twice the length of the larva. The remarkable eyes which this animal possesses- give 

 it a very odd appearance. They are placed at the extremity of club-shaped stalks, each of which 

 is nearly 2""" long. The distance between the eyes is 4.7""". In passing to the adult stage the 

 eye-stalks are much reduced. The outer antenna? have a short peduncle; along scale, armed 

 with stiff hairs on the inner margin, and a long fiagellum, all very much as in the adult prawn. 

 (PI. xii, and PI. xm, Figs. 40, 41.) The first pair of antenna? are much less like the adult form. (PI. 

 xn and Fig. 40). The stalk is longer and more slender than in the full-grown condition. The 

 flagella are short, the inner one still rudimentary, and the sensory hairs are retained. 



The carapace has developed on it a lateral furrow, which is surmounted by a conspicuous 

 spine placed on either side at a point one third the distance from the rostrum to the posterior end 

 of the carapace. The rostrum is short and stout, bent upward, and does not reach beyond a line 

 passing through the vesicula auditoria. The front of the carapace bears also a short dentiform 

 prodftss on each side below the rostrum. These are the only indications of the future spinous 

 armature of this region of the body. The abdomen and abdominal appendages are about as repre- 

 sented in Fig. 27. The telson is a short triangular plate, garnished with short bristles, and is 

 terminated by a pair of very small spines. The uropods are provided with a close, fringe of inter- 

 locking, plumose hairs, which are longest on the inner margin. The outer lamella is one-third 

 longer than the inner and three times as long as the telson. 



The first ami second maxilla? of this larva are represented in Figs. 2$ and 20. In Figs. 12, 19, 

 29, and 38 we have four stages in the evolution of the first maxilla, and we see that it undergoes 

 comparatively little change. No trace of a palpus (endopodite) was seen in the specimen exam- 

 ined (Fig. 29), the appendage consisting of*a small inner (coxopodite) and a larger outer knob- 

 shaped branch (basipodite), each armed with short tooth-like spines. The second maxilla, has also 

 the adult character. (Figs. 28, 42.) It consists of an elongated outer plate (scaphognathite), 

 fringed with a single row of plumose hairs; a palp-like endopodite, and an innermost lobulated 

 division (basipodite and coxopodite), each part carrying a few bristles. 



The first maxilliped of stage F is given in Fig. 30. It-consists of a basal portion (coxopodite), 

 which bears an inner and larger lobe (basipodite), having bristles on its proximal border; an exo- 

 podite tipped with a pair of bristles, and of an intermediate bud (endopodite) bearing a single 

 bristle. Part of the second maxillipeds is shown in PL xi and also in Fig. 31 (St. F.). The 

 exopodite is rudimentary. The outer segments are covered with spinons bristles. We see already 

 a resemblance between these appendages and their adult forms. (Figs. 43, 45.) The third pair of 

 maxillipeds are still the largest limbs. (PL xi, Mxp. m.) The terminal joint bears several long 

 spines. Compare with the adult limb seen in Fig. 40. 



The pereiopods are slender appendages, of which the third pair are longest, as in the adult; 

 the second are longer than the first; the fourth and fifth are rudimentary. One of the first pair 

 of pereiopods is represented in Fig. 33. This appendage is nonehelate, unlike the adult stage; all 

 its segments are armed with long spines, and there is a cluster of serrate bristles on the inner side 

 of the proximal end of the terminal segment, and near it, a similar cluster on the next. Similar 

 tufts of hair are found on the adult appendage. (PL xm, Fig. 47.) The terminal joint of the sec- 

 ond thoracic limb is shown in Fig. 32; the basal extremity of the third, the, fourth, and fifth are 

 given in Fig. 34. The second and third pair are. chelate; the fourth is rudimentary; the fifth is 

 still a bud. The abdominal appendages, excepting the sixth pair described above, are all uuira- 

 roous. (Fig. 27.) 



