246 



Cryptoniseid No. 2. 



(PI. C, fig. 3). 



Characters. — Body, as seen from aboTe, oblong fusiform in outline, broadest 

 in the middle, and tapering to almost an equal extent both anteriorly and posteri- 

 orly. Cephalic segment considerably narrowed in front, with the extremity narrowly 

 rounded; anal segment forming behind a rounded lamellar expansion divided into 

 7 coarse teeth. Eyes inconspicuous. Basal joint of antennulae forming behind a 

 very large laminar expansion divided into 9 closely crowded acute teeth; the 2 

 succeeding joints densely covered in front with small denticles. Antennae com- 

 paratively short, scarcely extending beyond the 2nd pedigerous segment, flagellum 

 much shorter than the peduncle. Coxal plates distinctly pectinate. Legs of nor- 

 mal structure, the posterior pairs rather slender, with the dactylus simple. Uro- 

 jDoda somewhat resembling in structure those in the corresponding stage of the 

 Dajida 3 ; the rami being linear in form and terminating in several denticles, outer 

 ramus, however, considerably shorter than the inner. Length of body 0.90 mm. 

 Found attached beneath the anal segment of ^Ega ventrosa M. Sars. 



Remarks. — This form somewhat resembles in its outward appearance some 

 of the Dajid larvae figured by Dr. Hansen in his account of the Isopoda of the 

 German Plankton Expedition, and the structure of the uropoda likewise approaches 

 that found in the larvae belonging to that family; but the structure of the 

 antennulae is essentially different, and agrees with that in the Cryptoniseid larvae, 

 and the oral cone lacks all trace of the sucking disc so characteristic of the 

 Dajid larvae. On account of these 2 latter characters and also of the structure of 

 the legs, this form ought certainly to be referred to the family Cryptoniscidce ; 

 but at present it is impossible to recognise its relationship to the several genera 

 comprised within that family. 



Occurrence. — All the specimens examined by me were taken from the 

 same species of iEga, viz., M. ventrosa M. Sars, and were invariably found 

 firmly attached to the lower face of the anal segment or telson, near the anal 

 opening, sometimes but a single specimen, sometimes 2 such in each iEga.^The 

 latter were collected by the aid of the dredge from a depth of 60 —100 fathoms 

 off the Nordland coast. 



