294 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



from the Ostracoda and used the name Entomosiraca as a group name 

 for the Siphonostoma and Lernaeoda. 



Claus used the word Entomostraca in a different sense. The Phyl- 

 lopoda, Ostracoda, Gopepoda and Cirripedia were collectively called the 

 Entomostraca. 



Professor G. O. Sars has divided the Ostracoda into the following 

 four sections: 1. Podocopa, 2. Myodocopa, 3. Cladocopa, 4. Platycopa. 

 All of the members of sections 2, 3 and 4 and a portion of those belong- 

 ing to section 1 are marine. 



Brady and Norman have divided the Podocopa into the following 

 families: 



Family I. — Gyprididce. 



Family II. — Bairdiidce. 



Family III. — Darwimilidce. 



Family IV. — Gylheridce. 



Family V. — Paradoxostomatidce. 



This article treats exclusively of the first and third families. 



FAMILY CYPRIDID^. 



^ 'Shell generally thin and horny; valves equal or but slightly une- 

 qual in size, surface usually smooth, or simply punctated; ventral 

 margins more or less sinuated; hinge margins edentulous. Eyes sim- 

 ple, usually confluent, sometimes wanting. Antennules (first anten- 

 nae) slender, usually seven-jointed, very fiexible, usually provided 

 with a number of long hairs forming a dense brush. Antennae (sec- 

 ond antenuse) pediform, geniculated, four- or five-jointed, clawed at 

 the apex, second joint mostly bearing an apical brush of hairs. Man- 

 dibles strong, apex strongly toothed, palp four-jointed, with a setifer- 

 ous branchial plate at the base. Two pairs of maxillae, the first pair 

 four digitate; its external branch distinctly two jointed, bearing a 

 large setiferous branchial plate; second pair small, composed of a 

 single prehensile lobe and palp, which in the female is generally sim- 

 ple, rarely pediform, is in the male prehensile. Two pairs of feet dis- 

 similar in structure, the anterior pair strong, ambulatory, directed 

 downwards, and having a long curved apical claw; posterior bent 

 backwards within the shell, and not used for motion. Caudal rami 

 usually well developed, elongated, very mobile, and bearing two or 

 three apical claws. Intestine forming two dilations, of which the an- 

 terior is provided with coecal appendages. Generative organs large, 

 and of complex structure, and partly extended within the valves; in 

 the male frequently a whorled sac connected with the testis; copula- 



