56 A Guide to the Zoological Collections in the 



its pair of appendages. The curious form Nebalia is a 

 link between these two divisions. 



a. CRUSTACEA ENTOMOSTRACA. 



[aac0tern GEitU-rii0£ 48], 



As the Entomostfaca are for the most part minute, 

 and can be properly examined only under the microscope, 

 they occupy but an unimportant place in the Museum 

 Gallery and cannot, therefore, be treated of at any length 

 here. 



There are four orders of the Entomostraca — namely, 

 the Phyllopoda, the Osiracoda, the Copepoda^ and the 

 Cirripedia. 



The species which constitute the three first-named of 

 these orders are almost all too minute for exhibition. 



. i. CRUSTACEA ENTOMOSTRACA PHYLLOPODA. 



The Phyllopoda are represented in Case 48, by two 

 species of Apus from Europe. 



In Apus the body is made up of a large number of 

 ring-like segments, the first twenty or more of which are 

 covered over dorsally by a large shield-shaped carapace, 

 and bear each a pair of bilobed leaf-like feet ; while the 

 last five or six are uncovered and are devoid of append- 

 ages, and project behind in the form of a short ringed 

 cylindrical tail which ends in a long fork. At the front 

 of the carapace are seen the large eyes. 



ii. CRUSTACEA ENTOMOSTRACA OSTRACODA. 

 The Ostracoda are marine forms usually of a size far 

 too small for exhibition. To illustrate their size some 

 specimens of Cypridina are shown in Case 48. 



iii. CRUSTACEA ENTOMOSTRACA COPEPODA. 

 The Copepoda inhabit both salt-water and fresh-water, 

 and they also are for the most part toos mall for exhibi- 



