MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 345 



Figs. 14 and l(i, which represent the first and third maxillipeds of the right side, as seen from 

 below. The endopodites of the second and third pairs possess four joints, of which the terminal 

 one carries setre. There is one pair of thoracic limbs consisting of a stout locomotive exopodite, 

 similar to that of the second and third maxillipeds just described, and of a very short, indistinctly 

 segmented eudopodite. The latter is armed with two terminal and three lateral plumose hairs on 

 the inner side. 



B. First z<wa or second larva (length, =5 mm ). Five or six hours after hatching the pro- 

 tozoea moults into a form which superficially resembles the raacronran larval type. (PI. VIII, 

 Fig. 17.) The carapace, of this larva has grown down so as to cover the basal joints of all the 

 appendages, and it also extends behind them. The rostrum is reduced to from one-half to two- 

 thirds its former size, and does not surpass the autenual hairs. 



There is still put one thoracic segment with its appendages. All the abdominal segments are 

 formed, but none show any traces of limbs. The lateral spines of the first and second somites are 

 missing, but the median unpaired spine of the latter is greatly developed, and extends to nearly 

 the end of the third somite. The sixth somite, which carries the zoeal telson, is equal in length to 

 the third, fourth, and fifth combined. The fan-shaped telson, viewed from below, is represented 

 in Fig. 20. Comparing this with Fig. 11, we observe that it is no longer conspicuously forked. 

 The median notch has a short unpaired spine. There are six pairs of feathered hairs, the outer 

 ones still being rudiments exactly as in the first larva, and a non-plumose spine which ends the 

 series; the three rudimentary spurs seen in Fig. 11 being wanting. The eyes, which have acquired 

 short stalks, protrude slightly. 



The antennae are shorter and are now no longer so important as organs of locomotion. The 

 terminal joint of the inner antenna is reduced, but otherwise this appendage is but little changed. 

 The outer antenna ends in a stout hook, which is succeeded, on the indented margin of the inner 

 side, by a series of eight feathered hairs. The second joint of this appendage also bears a serrated 

 hooked spine at its outer extremity. The mandible is without a palp. It has a serrated edge, 

 and a prominent, inferior, compound tooth (Fig. 18). 



The inner branch (coxopodite) of the first maxillae (Fig. 19) carries three simple and three com- 

 pound spines, while the outer division consists of three segments with stout, plumose hairs, as shown 

 in the figure. The second maxilla? (Fig. 21) are considerably altered from the form shown in Fig. 10. 

 There is an outer lobe (scaphognathite), bearing one large hair directed backwards and at least 

 four others which point in the opposite direction. The inner portion is tabulated into six or more 

 parts, all of which are well provided with stiff hairs.* 



The first maxilliped is shown greatly enlarged in Fig. 22. Examining this in connection with 

 Fig. 14, we find that the exopodite consists of one segment and bears a limited number of hairs 

 (here twoj at its apex. The endopodite is segmented and carries numerous hairs, which are 

 continued in small tufts along the inner margin to the base of the limb. The chief swimming 

 organs are the first and second maxillipeds and the first pair of thoracic legs. The inner branch 

 of the latter is considerably developed, and nearly equals the expedite in length. 



There is a large irregular spot of red pigment on each side of the anterior half of the body 

 just above the base of the third maxilliped. The lobes of the liver (L) begin now to show dis- 

 tinctly through the carapace. The food yolk, which is present in small quantities in the stomach 

 of the protozoea (Fig. 25), is finally absorbed. It was probably owing to this and to the fact that 

 I gave the larva. 1 , no food that suited their taste that they never reached the second moult, although 

 they passed a number of days in this condition. In course of several trials the animals at this 

 stage always became greatly crippled by particles of organic matter adhering to their body and 

 invariably starved. For later stages, therefore, connecting this zoe'a with the adult, we have to 

 rely upon larva? collected at the surface of the ocean. 



C. J\[ysis or Schizopod stage. It is evident that the zoe'a of the stage B passes into a mysis- 

 like form through the intervention of one or more moults, and we have two larva? already noticed 

 belonging to the close of this period. They were collected by at Beaufort, N. C., July 14 and 15, 



" Thu distal or terminal lobo represents the endopodite; the lobes next this stand for the basipodite, while the 

 second (f) proximal division at the base of the appendage correspond to the coxopodite. 



