OF DENISON UNIVERSITY. II 



II. Late Larval History of Cypris Herricki, Tur. 



[Plate I, fig. 33-39; plate II, fig. 40-42-] 



Historical. — As far as I ca;i discover we are indebted to Profes- 

 sor C. Clans, for all we know about the development of the Ostraco- 

 da.' His researches upon Cypris ovum [Cypria opthalmica (J urine) 

 Brady] led to the discovery that ihis form passes through nine larval 

 stages. This Cypria escapes from the egg as a free swimming nau- 

 plius; but the nauplius differs from the typical nauplius in two im- 

 portant particulars : The animal is enclosed in a bivalve shell and 

 none of the appendages are biramous. In the second stage the man- 

 dible attains its adult form and the first pair of maxillae and the first 

 pair of feet appear. The maxilla resembles somewhat a phyllopod 

 appendage. In the third stage no essential change occurs. In the 

 fourth stage the first pair of maxillae attain their final form and the 

 second pair of maxillae appear. The rudiment of the post-abdomen 

 is also visible. In the fifth stage the second pair of maxillae develop 

 a blade and function as an ambulatory organ. In the sixth stage the 

 second pair of maxillae lose their ambulatory function, and at the 

 same time the second pair of feet is formed. In the seventh stage all 

 appendages have attained about the permanent form. The next two 

 stages are characterized chiefly by internal changes. 



In this connection it is not intended to discuss the early slages of 

 Cypris Herricki. These remarks will be confined to what corresponds 

 to the seventh to ninth ecdyces of Cypria opthalf>iica, Jurine. Not 

 only that, but the remarks will be restricted to the external morpholo- 

 gy. It is hoped to discuss the internal anatomy in a subsequent 

 paper. 



The earliest stage here discussed has been compared to the 

 seventh stage of cypria opthalmica, Jurine, because in that stage the 

 appendages have attained about their permanent form ; but it must 

 not be supposed that in this Cypris there are only two subsequent 

 larval stages. These stages are tabulated in the following table : 



^ Zur Kenntnis der Jungenforinen von CypHs ovum. Zeit. f. unss. Zool. Bd. 

 XV, 1865. 



Beitrage zur Kenntnis d. Ostracoden. Entwicklungsgeschicte von Cypris 

 otniin. ScJiriftcn d. Gcscll. zur Befdrdcrting d. gesamm. Natiirwiss. zu Marburg, 

 Vol. IX, 1868. 



Untersuchungen zur Erforschung der genealogischen (Irunlage des Crusta- 

 ceen Systems. Wien 1876. 



