REPORT ON THE SCHIZOPOD.\. 



149 



Hence the species would seem to have a rather extensive clistrihntion, ranging, as 

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



DEVELOPMENT OF EUPHAUSIID^E. 



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

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

 forms of Macrura, the three following schizopodous genera : — Cyrtopia, FurciUa, and 

 Cahjptopis. The first of these he ranks among the Euphausiidse, whereas the two others 

 are described in an Appendix to the Mysidse together with the spurious genus Zo'ea (first 

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

 represent but different stages in the development of Euphausiidse, the genus Calyptopis 

 beino- an earlier, the genus Cyrtopia a later, and the genus FurciUa an intermediate 

 stage. In 1869 Metschuikoff 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 Nauplii, having a rounded, unsegmented body with only three pairs of 

 developed limbs, viz., the two pairs of antennae and the so-called mandibular legs. Thus 

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

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

 and the Mctanauplius 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 Euphausiidas. The Nauplius, Metanauplius, 

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

 of examining, whereas the following will all 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 Euj^hausiidse : — 



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



1 Ueber einige Schizopodeu und niedere Malacostraken Messina's, Ztilschr.f. uiss. Zonl., 1863. 



2 Ueber ein Larvenstadium von Euphausia, Zdtschr.f. wiss. Zrol., Bd. .\i.\. 



3 Ueber den Naupliuszustand der Euphausia, Zeitschr. f. wiss. ZooL, Bd. .\.\i. 



