410 CRUSTACEA ENTOMOSTRACA. 



Sixth series (Fam. 17). 



Fam. 17. Choniostomatidae. Minute Copepods which live in the 

 brood or branchial cavities or elsewhere about the bodies of different 

 Malacostraca, whose blood they suck. The body, especially that of 

 the fully developed female, is more or less globular, and without seg- 

 mentation, though a transverse groove on the ventral surface marks 

 the limit of the cephalothorax, and in one genus the abdomen is 

 distinct. It is often partially clothed with hairs. The anterior antennae 

 are small, the posterior very minute. Mandibles simple and contained in 

 a conical proboscis terminating in a membranous cup. 1st maxillae minute 

 and biramous, on the outer sides of the proboscis. The second maxillae 

 and maxillipeds are generally powerful and prehensile. Two pairs of 

 minute biramous legs and the pair of caudal appendages project from the 

 globular posterior region. The male is often less than ^rd the length of 

 the female and is attached to it or to the body of the host by a stalk 

 secreted by a gland lying in front of the proboscis. The vasa deferentia 

 open, according to Hansen, between the swimming legs of the anterior pair. 

 The eggs are contained in numerous ovisacs which are generally not 

 attached to the body of the female. A " nauplius " stage, though 

 with only two pairs of appendages (cf. Achtheres, Lernaeopodidae) is 

 passed through in the egg and the larva is hatched in the " cy clops 

 stage " with the mouth and anterior appendages like those of the 

 adult, but with large swimming feet, and 1 or 2 free thoracic seg- 

 ments 'and a 3-jointed abdomen. The larvae attach themselves to a host 

 by a secretion of the frontal border of the cephalothorax, and in some 

 species either the female alone or both sexes pass through a pupal stage, 

 in which the appendages are ill-developed or absent, and the contents 

 of the body appears to undergo a process of histolysis. After the pupal 

 skin is shed the adult structure is complete. Stenothocheres Hans., 

 abdomen distinct, in marsupia of amphipod family Stenothoidae. 

 Homoeoscelis Hans., in branchial cavity of Cumacea. Sphaeronella 

 Salensky, in marsupia of amphipods, isopods and Cumacea, 34 spp. de- 

 scribed. Choniostoma Hans., maxillipeds rudimentary ; in branchial 

 cavity of the decapod Hippolyte. Mysidion Hans., in marsupia of 

 schizopods. Aspidoecia Giard and Bonn., attached to the outer surface 

 of the schizopod Eryihrops. 



Sub-order 2. BRANCHIURA.* 



Carp-lice. Copepods with large compound eyes, and a 

 suctorial tube about the mouth ; with jour pairs of elongated 



* Jurine, Memoire sur 1'Argule foliace, Annales du Museum d'hist. nat., 

 Tom. VII., 1806. Fr. Leydig, Ueber Argulus foliaceus, Zeitschr fur wiss. 

 Zool., Tom. II., 1850. E. Cornalia. Sopra una nuova specie di crostacei 

 sifonostomi, Milano, 1860. C. Glaus, Uber die Entwickelung, Organization 

 und systematische Stellung der Arguliden, Zeitschr. fur wiss. Zool., Tom 

 XXV., 1875. F. Leydig, Ueber Argulus foliaceus, Arch. f. Mikrosk. 

 Anat., T. 33, 1889. Nettovich L. v. Neue Beitrage zur Kenntniss d. 

 Argulidae Arb.aus dem Zool. Inst. Wien. Bd. 13 (1900) p. 1. Wilson C. B., 

 North American parasitic Copepods of the family Argulidae (with 

 Bibliography) Proc. U.S. Nat. Museum, vol. 25 (1903) p. 635, and a new 



