Mr. J. D. Dana on some genera of Cyclopacea. 



181 



XXIII. — Notice of some Genera of Cyclopacea. By J. D. Dana. 



As a preface to the descriptions which follow, a classification of 

 Crustacea is here given ; it is made out so as to exhibit to some 

 extent the parallel relations of the several orders and subdivi- 

 sions. 



CRUSTACEA. 



Subclassis I. 

 PODOPHTHALMIA 

 Ordo l« Decapod a. 

 Tribus 



1. Brachyura. 



2. Anomoura. 



3. Macroura. 



Ordo 2. Schizopoda. 



Tribus 



1. Stomapoda. 



2. Diploopoda. 



Subclassis II. 

 EDRIOPHTHALMIA. 

 Ordo 1. Choeistopoda*. 

 Tribus 



1. Isopoda. 



2. Lsemipoda. 



3. Amphipoda. 



Ordo 2. Entomosteaca. 



Subord. 1. 



GNATHOSTOM ATA f 



Tribus 



1. Branchipodacea. 



2. Limnadiacea. 



3. Daphniacea. 



4. Cyclopacea. 



5. Cypridacea. 



Subord. 2. 



COEMOSTOMATA J, 



Tribus 



1. Caligacea. 



2. Lernaeacea. 



3. Nymphonacea. 



Subord. 3, 

 Meeostomata §, 



Tribus 

 1. Limulacea. 



Ordo 3. Teilobita. 



Subclassis III. 

 MANDYATA | 



Tribus 

 1. Cirripeda, 

 or 



Balanaceaf. 



Order ENTOMOSTRACA. 

 Tribe Cyclopacea. 



To avoid explanations in the following descriptions, we here 

 enumerate the prominent external characters of this tribe. 



Body jointed, the carapax not prolonged beyond the joint to 

 which it belongs ; abdomen not innexed. 



* From xapio-Tos, separate, and novs,foot, alluding to the fact that the 

 pairs of feet belong each to a distinct segment of the body. 



f From yvaOos, jaw, and orofia, mouth, alluding to the mouth being fur- 

 nished with proper mandibles and maxillae. 



I From Kopfios, trunk, and aropa, mouth, the mouth having the form of 

 a moveable trunk 



§ From firjpos, thigh, and oro/ia, mouth, the basal joints of the legs con- 

 stituting the jaws. 



|| From navdvt), a cloak, alluding to the covering in which the body of the 

 animal is inclosed. 



Tf The Cypris-like young of several Anatifce were collected and figured 

 by the writer, and the metamorphosis traced to the adult state. When first 

 found swimming free in the ocean, they were taken for a new genus allied 

 to Cypris, so similar are their forms. The fact that the body and legs of 

 the Cirripeda shed their skin, is further evidence of the propriety of placing 

 this group with Crustacea. 



The pedicel of the Anatifce corresponds to a pair of antenna? in the young; 

 the animal attaches itself by the sucker-like disc terminating these organs 

 before the metamorphosis commences, and in a group of Anatifce all the dif- 

 ferent stages may be observed, from the pair of distinct antenna? to the fixed 

 simple pedicel. 



