124 REPORT OF NEW JERSEY STATE MUSEUM. 



fourth thoracic legs uniramose, second and third biramose. 

 Fourth thoracic segment without dorsal plates. Genital segment 

 simple, without plates or processes. Abdomen one to many seg- 

 mented. Young of both sexes with frontal filament for attach- 

 ment during chalimus stage. Anal lamellae strongly flattened 

 and armed with long plumose setae. 



Caligus tenuis (Leidy). 



Chalimus tenuis Leidy, Proc. Acad. Nat. Sci. Phila., 1889, p. 95. Beach Haven, 

 Nezv Jersey (on young Leptocephalus) . 



Description. — 'Cephalothorax nearly twice length of breadth, 

 obcordate and proportionately much narrower than in Chalimus 

 scoDiberi. Frontal segment narrow, not prominent laterally, and 

 biarticulate antennae concealed beneath. Abdomen half length of 

 cephalothorax, shows three conspicuous divisions, and short 

 caudal appendages end in three minute setae. Abdominal feet 

 ending in biramous leaf-like segments fringed with short setae. 

 Rostrum linear and almost long as cephalothorax. Whole length 

 1. 125 mm., of cephalothorax 0.5 mm. (Leidy.) 



Remarks. — This species is only known from the above account, 

 having been taken on a larval fish Leptocephalus (Atopichthys), 

 to the tail fin of which it was attached by means of a long fili- 

 form rostrum. In this respect it was thought to resemble 

 Chalimus scomberi as figured by Baird, rather than by Bur- 

 meister. • 



Family ERGASILID^. 



Head of moderate size, rounded. Antennae formed of five or 

 more articulations. Mouth parts poorly developed. Body ovoid 

 or pyriform in contour, and thorax sometimes much enlarged 

 laterally. Feet very small, branched, not attached to a basal 

 joint extending across under surface of thorax in form of broad 

 plate, but basal joints detached from one another. Abdomen 

 well developed. Parasitic. 



