MEMOIRS OF THE NATIONAL ACADEMY OE SCIENCES. 357 



Stomatopod larvae or Ericbtliida;, as tbey were named before their larval uature was susi>ected, 

 bave been divided into four {jeiiera, Erichtlioidina, Ericlitlius, iiquillcriclithiis, and Alima. Of tbese 

 four the first, Ericlithoiilina, is siniidy a .yoiuifjcr staj^e in the life of the Ericlitlnis, and the third, 

 Sqitillcriclitlius, a fnll.v-frrown larva, of the Erichflntu type, so that the genera hecoine reduced to 

 two, Erichthns and Alima. Of these two fjenera, one, Alitna, is much more sbari)ly defined than 

 tlie other, ^/Jc/iY/iKS, which contains a number of diverfjent types, of which 1 have shown that 

 five may be clearly distinguished, and I have j)roi)osed, for these five, nauies which indicate the 

 adult genus to which each corresponds. I have shown tiiat there are many reasons for believing 

 that all Alimi are (iquilla larvie; Alimerichthus, tlie larva; of Cliloridella; Ericlithalinia, the larvae 

 of Corouidd ; Lysiericlitlins, the larva', of Lysiosqnilla, and I'.seuilerichtlius, thi', larvae of rxciidi)- 

 squilla. Tiie remaining larval type may be distinguished from the Li/sirrivhthus by tiie shallow- 

 ness of its caraiiace, which is not at all infolded, and by the position of its postero lateral 

 spines, whicli arise very close to the dorsal middle liiu'; while it may be distinguished from the 

 Pseitdertclithus larva^ by the length of the [)osterolateial s[)iues, which are at least half as long iis 

 the carapace, and also by the fact that the telson is wider than long and longer than the long 

 outer spine of the nropod. For this larval type, which was represented in the 67(a//e«//er collec- 

 tion by many specimens, I ])roposed the name Gonerivhthm, giving, at the same time, many 

 reasons for regarding it as the larva of the genus Gonodactylus. Several of these larvai were 

 selectetl and shown in Tl. xir, Fig. 5, PI. xiii, Fig. !), and Tl. XV, Figs. I and 5, of my report; and 

 I pointed out that in ail of these larvae, as in the young (louodactylus, the sixth abdominal .somite 

 has a pair of submedian spines near its i)osterior eilge, and its posterolateral angles are i>rodnced 

 into acute spines. The telson is .slightly wider than long, and its submedian spines are long and 

 slender, but shorter than they are in Pseuderichthns. The telson is notched on the middle line, 

 and there are from fourteen to twenty small secondary spinnles on its posterior edge, between the 

 submedians. There is one small secoiulary spinule internal to the base of the lateral marginal 

 spine, another internal to the base of the intermediate,^ud a third miJway between this and the 

 submedian. 



In ri. XV, Figs. 5 and 0, of my report, as in the young Gonodactylus, the outer edge of the 

 proximal joint of the exopodite of the nropod is fringed by nine marginal spines, the terminal one 

 lont^est, and the outer si)ine of the basal i)rolongation is mnch longer than the inner, but not so 

 li'hg as it is in Pxcudcrichthuii. A com])arison of the telson of the young Gonodactylus with that 

 of the other larval types will show that the one now under discussion is the only one which exhibits 

 this resemblance, and as this larva never exhibits any traces of marginal spines on the dactyle of 

 the raittorial claw it nnist pertain to some known adult with an unarmed dactyle or else to a new 

 genus. It is not probable that a larval type which is so common pertains to an unknown adult 

 genus. The larvaj are not ProfosquUla; as this genus has the telson fused with the sixth abdom- 

 inal somite, while it is free in the older larvic; nor are they PHeudt)squiUa\ for they have no movable, 

 spinnles on the tips of the submedian spines of the telson; and as all the other genera of Stoma- 

 topods except Gonodactylus have the dactyle armed, the only remaining genus is Gonodactylus, 

 anil the structural characteristics of the oldest larv;n imlicate that they are the young of species 

 in this genus. 



Led by these considerations I did not hesitate to speak of the.se larvie, in the Challcnf/er 

 report, as Gonerichthi, or young Gonodactyli, and to give this larval form as one of the diagnostic 

 characteristics of the genus. This determination rests, however, ui)on circumstantial or indirect 

 evidence; and, while the evidence is quite conclusive, I was nevertheless ])leased to obtain more 

 l)Ositive proof from the larvse which I reared from the eggs of Gonodactylus chirnfira. 



Like many othei' Crustacea which iniiabit the (loral i-eefs, this species has its metamorphosis 

 abbreviated and it hatches from the egg in an advanced condition. It is shown just before iiatcliing, 

 seen from behind in PI. xiv, Fig. 1, and from in front in Fig. 2. The large yolk covers the dorsal 

 surface, and the larva is doubled on itself, so that the telson and the tip of the abdomen are visible 

 in a front y'wvr. The first t'lvo. abdominal somites are indicated before it leaves the egg, and the 

 first five pairs of abdotnimil appendages are fully developed, although the other appen<lages, with 

 the exce|>ti(in of the mandibles and the large raptorial second maxilliiieds, are either absent or rudi- 

 mentary The eyes are large, and even before hatching they are movable, although they are 

 nearly sessile. « 



