neio Parasitic Gopepods on Fish. 15 



both sexes were found, the pigmy male being single, attached 

 usually to the genital segment under the arms of attachment 

 (PI. VI. fig. 1). 



Female. — Cephalothorax in the same straight line as the 

 body, rounded anteriorly, somewhat dilated. Second maxilli- 

 peds equalling in length the cephalothorax, directed down- 

 wards and forwards, widely separated from base to extremity, 

 where they unite and give rise to a well-marked stalked disk 

 of attachment ; on the under surface of each arm is a process 

 giving off four elegant elongated filaments. Body (genital 

 segment) oval, constricted in front; from the posterior extre- 

 mity on either side is a prolonged bifid appeniage; centrally 

 two small caudal lanceolate plates are present. 



Length 6 millim. 



Male (PI. VI. fig. 3). — About 1 millim. long. Cephalo- 

 thorax distinct from the body, which is long and indistinctly 

 segmented, terminating in two short caudal processes. 

 Anterior portion of the cephalothorax carrying the mouth- 

 organs and antennae. Anterior antenna' three-jointed, with 

 three fine bristles at the end of the last joint. Poste- 

 rior antennce terminating in a thickened joint with a short 

 tubercle on outer side, and the inner with a small recurved 

 hook. Mandible long, with bifid end ; extremity of mouth 

 finely ciliated. Both pair of maxillipeds large ; the first 

 provided with a very strong hook, the second with a much 

 smaller one. 



1 have not either the plate or description of " Stecnstrup 

 and Liitken " to refer to with regard to their B. appendicu- 

 lata, and have therefore provisionally called this species as 

 above. 



EXPLANATION OF THE PLATES. 

 Plate I. 



Fiff. 1. Bomohchus triceros, 2, sp. Q., from back, magnified. 



1 a. From underside, more enlarged. 1 b. Hamulus. 1 c. Pos- 



terior antemije. Id. Firit perasopod. \c,f,g. Third 

 fourth, and fifth pera3opods. 

 Fiy. 2. Boviolochus tctrado?iis, sp. n., 2 > from back, enlarged. 



2 a. Antennae with mouth-organs, seen from beneath, much 



enlarged. 2 b. Terminal joint of posterior antenua3. 

 2 c. Extremity of second maxilliped. 2d,e,f,ff. Second 

 third, fourth, and fifth peraeopods. 2 h. Caudal plate, 



Plate II. 



Fi(/. 1. Caligus parvus, $, sp. n., enlarged. 



1 «. Under surface of cephalothorax. \b. Last joint of first 

 perseopod. 1 c, d. Second and third peraeopods. 1 e. Caudal 

 plate. 



