MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 359 



sixth abdominal somite bas separated from the telson, but its appendages are not yet developed. 

 The scale of the antenna is now fringed with hairs, and the eyes are divergent, with well devel- 

 oped stalks. The raptorial claws have greatly increased in size and are beginning to approximate 

 to the adult form, while at the earlier stage they closely resembled the chela' of the third, fourth, 

 and fifth pairs of maxillipeds of an adult Stomatopod. From this time on to the end of its larval 

 life the yonug Erichthus of Gonodactylus ch iragra presents the characteristics of that larval type 

 for which I have proposed the provisional name Gouerichthus; and, while the resemblance grows 

 stronger as the larva grows older, it is unmistakable even now, and still clearer after the next molt, 

 wbeu it assumes the form sbow/n in PI. xiv, Fig. (5, from above, and obliquely from below in PL xv, 

 Fig. 10. 



The autennulary flagella are now beginning to elongate, and that of the antenna is now rep- 

 resented by a bud, but there are no new appendages, although the sixth abdominal somite is uow 

 indicated. Although it is very much younger than he Gonericbthi shown in my Challenger report 

 in PI. XV, Figs. 1, 5, 6, and 11, it resembles these larvae in the following features as well as in 

 many minor points : The rostrum is long and reaches beyond the tips of the antennules, and it lias 

 four or five median teeth on its ventral surface. The anterolateral angles of the carapace end in 

 acute spines pointing forwards, and the anterior edges are inclined towards each other, so as to make 

 at the base of the rostrum an angle a little greater than a right angle. The lateral borders of the 

 carapace are nearly parallel, and the posterolateral spines long, slightly divergent, and with a 

 small acute spine external to the base of each. The carapace covers all the five thoracic somites 

 and all or nearly all of the first abdominal, and its posterior border is transverse. The median 

 dorsal spine, which was carried on the posterior edge of the carapace of the younger larvae (Figs. 3, 

 4, and 5 of PL xiv), has disappeared, although it persists until a much later stage, in the Iarva3 

 shown in Figs. 1, C, and 11. of the Challenger report. The hind body is now nearly three-fourths 

 as wide as the carapace. 



The lateral margins of the telson still carry, as they did during the earlier stages, four nearly 

 equal marginal spines on each side; of these the most anterior is the external, the next the inter- 

 mediate, the third a secondary spinule, and the fourth, which, at the stage shown in Fig. 6, PL xiv, 

 forms the posterolateral angle of the telson, is the submedian. The posterior border between the 

 submedians is very slightly notched and nearly transverse. All the Challenger Gonerichthi are 

 very much older than this larva, and their telsons are more developed. The spines especially are 

 much more elongated ; but in Figs. 5 and of PL XV of the report the secondary spine can be 

 clearly recognized about halfway between the snbuiediau and the intermediate. 



With the assumption of the form shown in PL xv, Fig. 10, the habits of the larva undergo a 

 sudden change. Up to this time, while able to 'swim briskly about by the use of their abdom- 

 inal appendages, they spent most of their time near the bottom of the aquarium, seldom going 

 up more than an inch or two, although they are quite able to reach the top of the water, which 

 was about 10 inches deep, and when masses of Nudibranch eggs were suspended hear the surface 

 of the water they quickly discovered and fastened upon them. 



Up to this time, also, they were peaceful and did not attack each other. Several hundred sur- 

 vived the molt which precedes the beginning of their pelagic life, but all of them soon died and none 

 passed this stage, which is the one shown in Fig. 10. They now left the bottom, and became rest- 

 less, swimming continually at all levels in the water. They refused to touch the eggs of which up to 

 this time they had been so fond, and I could find nothing else which suited their appetites, but their 

 proper food is, beyond question, small swimming animals of some sort, for they now began fighting 

 among themselves, and when two met they would seize each other with their raptorial claws, and 

 then tumble over and over together, until they struck the bottom, when both died. The survivors 

 would not touch the dead bodies, although most of them soon shared the same fate, and the rest 

 became weak and soon died. 



At the same time that I was studying the growth of the captive larvrel captured several older 

 ones in the surface net, and one of them somewhat older than Fig. 10 is shown in Figs. 11 and 12. 

 The third, fourth, and fifth maxillipeds are now developed and are like those of the adult; and 



