MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 347 



F. ytaHtigopun stage. — After it had been kept three days this larva passed tliroufjh a moult, 

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

 jointed, the lifth remaining as a bud. The flagelluni (endopodite) of the second jiair of anteinnc 

 uncoils and speedily Icngtiiens. The terga of the lirst 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. 2(), 27, ;>(), and .''>1 are from this stage. 



G. Maxtiffopus .stage [IM. xi, Figs. 28, 20, .•52-34, PI. Xii|, (Length = it""").— An older larva, 

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

 long trailing antenna' (flagella of the outer i)air), the actual length of which is about 1 inch, which 

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

 it a very odd appearance. They are pla(;ed at the extremity of club-shaped stalks, cavAi of which 

 is nearly 2"""' long. The distance between the eyes is 4.7"'"'. In jjassing to tiu^ adult stage the 

 eye-stalks are much reduced. The outer antennae have a short i)eduncie; along scale, aimed 

 with stilV hairs on the inner margin, and a long llagellum, all very much as in the adult i)rawn. 

 (PI. XII, and J'l. xiii, Figs. 40, 41.) The lirstpair of antennai are much less like the adult form. (PI. 

 XII and Fig. 4(t). Th« stalk is hmger and more slender than in the full grown condition. The 

 tlagella 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 jwint one third the distance from the rostrum to the jiosterior end 

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

 passing through the vesicula auditoria. The front of the carai)ace bears also a short dentiform 

 process on each side below the rostrum. These are the only indications of the future si)inous 

 armature of this region of tlu^ body. The abdomen and abdominal appendages arc 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 i)rovided with a clo.se fringe of inter- 

 locking, ])lumose 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 and second maxilhe of this larva are represented in Figs. 2S and 29. In Figs. 12, 19, 

 29, and .VS 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 (endoi)odite) 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), eacli armed with short tooth-like spines. The second maxilla hasal.so 

 the adult cliaracter. (Figs. 2.S, 42.) It consists of an elongated outer jdate (scapliognathite), 

 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. ^0. It consists of a l)asal 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 (endojjodite) bearing a single 

 bristle. Part of the second maxillipeds is shown in PI. xi and also in Fig. .'>1 (St. F.). The 

 exopodite is rudiment.ary. The outer .segments are covere<l with spinous bristles. \\'{\ see already 

 a resemblance between these appendages and their adult forms. (Figs. 4.'5, 45.) The third pair of 

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

 spines. Compare with tht! adult limb seen in Fig. 4(5. 



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 i)ereiopods is represented in Fig. 33. This api)endage is non(Oielatt>, 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 a])])endage. (PI. xni, Fig. 47.) The terminal .joint of the sec- 

 ond thora(uc limb is shown in Fig. 32; the basal extremity of the third, the fourth, and lifth are 

 given in Fig. .'54. The seconil 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 nnira- 

 mous. (Fig. 27.) 



