EEPORT Oy( THE SCHIZOPODA. 149 



Hence the species would seem to liave a rather extensive distribution, ranging, as 

 it does, from the North Atlantic to the Pacific Ocean. 



DEVELOPMENT OF EUPHAUSIID^. 



In his great work on the Crustacea of the United States Exploring Expedition, Dana 

 has estabhshed, exclusive of certain other spurious genera, apparently founded on larval 

 forms of ilacrura, the three following schizopodous genera : — Cyrtojoia, Furcilia, and 

 Calyptopis. The first of these he ranks among the Euphausiidag, whereas the two others 

 are described in an Appendix to the Mysidse together with the spurious genus Zoca (first 

 larval stage of Brachyura). As first shown by Professor Claus,^ all these three genera 

 represent but diff'erent stages in the development of Euphausiid^, the genus Calyjytojyis 

 being an earlier, the genus Cyrtopia a later, and the genus Furcilia an intermediate 

 stage. In 1869 Metschnikofi" described^ a still earlier stage in the development of 

 Euphausia, and in 1871 the same author stated"* that the young of Euphausia are 

 hatched as true NaupHi, having a rounded, unsegmented body with only three pairs of 

 developed limbs, viz., the two pairs of antennse and the so-caUed mandibular legs. Thus 

 not less than five principal stages occur in the larval development of the EuphausiiclEe. 

 The two first we shall designate, in accordance with earlier authors, the Naupliiis stage 

 and the Metanauplius stage. For the three succeeding stages I have seen fit to apply 

 the generic denominations suggested by Dana, since none of these stages fully correspond 

 with the Zoea and Mysis stages in other Podophthalmia. Hence .we have the following 

 successive stages in the development of the Euphausiid^. The Nmiplius, Metanauplius, 

 Calyptopis, Furcilia, and Cyrtopia stages .The first of these I have not had opportunity 

 of examining, whereas the following will aU be found described in detail below, as well 

 as several intermediate or connecting stages. 



I append here a short diagnosis of each of the principal stages peculiar to the 

 development of the Euphausiidse : — 



1. Nauplius Stage. — Body oval, unsegmented. No compound eyes. Three pairs of 



' Ueber einige Scliizopoden und niedere Malacostraktn Messina's, Z itschr.f. tnUs. Zonl., I81j3. 

 - Ueber ein Larveustadium yon Euphausia, Ztilschr. f. u-iss. Z'ol., Bd. xi.\. 

 5 Ueber den Xaupliuszustand der Euphausia, Zeitschr. f. iciss. Zoo!., Bd. x.\i. 



