368 



ARTICULATA : CRUSTACEA. 



ter fishes, and is common on the pickerel, especially on 

 the gills. The two last-named genera belong to the 

 Siphonostoma of authors. And to the Siphonostoma 

 also may be referred the strangely -formed parasites Ler- 

 nea and Lerneonema (Fig. 501), etc., formerly described 

 under the name of Epizoa. 



The OSTRACODA (Cypr-iS) etc.) have no branchiae, nor 

 any modification of limbs to serve for branchiae so far as 

 is apparent ; the body does not exhibit distinct segments, 

 and is wholly inclosed in a bivalve shell. The name is 

 from the Greek ostrakon, a shell. Cypris is very minutej 

 and abounds in ponds and pools. Fossil shells of extinct 



FIG. 503. 



FIG. 502. 



Acorn Barnacle appendages 

 drawn in. 



FIG. 504. 



Acorn Barnacle, Balanus, with 

 appendages extended. 



Stalked Barnacle, Lepas. 



