_36_ 



gramma. In its movements it is more active than most other species, and 

 thus deserves the specific name given to it by Thorell. 



Distribution. Coast of Bohuslan (Thorell), British Isles (Brady), coast 

 of France (Canu). 



5. Notodelphys tenera, Thorell. 



(PI. XVIII, 1). 

 Notodelphys tenera, Thorell, I. c. p. 36, PI. Ill, 3. 



Specific Characters. Female. Body comparatively slender, with the 

 anterior division somewhat dilated in its anterior part. Cephalic segment 

 exceeding in length the 2 succeeding segments combined, and conically pro- 

 duced in front. Incubatory pouch, when fully developed, of rather a charac- 

 teristic shape, being almost gibbously dilated in the middle and fully as broad 

 as it is long. Caudal rami rather narrow, and exceeding the anal segment 

 by about ! /4 of their length; apical setae unusually slender and elongated; 

 bristle of outer edge occurring close to the apex. Both pairs of antennas 

 conspicuously more slender and elongated than in the other known species. 

 Last pair of legs with the proximal joint short, but rather broad, and having 

 the digitiform process large and extended obliquely outwards; distal joint 

 very narrow at the base, but gradually widening distally, so as to assume a 

 somewhat claviform shape, spine and seta issuing close together from the 

 inner distal corner. 



Body in the living animal whitish hyaline, with the ripe ova yellowish 

 red in colour. 



Length of adult female 3.20 mm. 



Remarks. The present species may be recognised by the unusual slend- 

 erness of both pairs of antennae and the rather elongated caudal setae. The 

 shape of the caudal rami and the position of the outer-edge bristle is also 

 peculiar. Another easily observable distinguishing character, not mentioned by 

 Thorell, is derived from the shape of the incubatory pouch, which differs 

 conspicuously from that in any of the other known species. 



Occurrence. I have taken this form occasionally in 3 widely remote 

 localities on the Norwegian coast, viz., Riser, Trondhjem Fjord, and Valder- 

 sund on the Nordland coast. The specimens were found in the branchial 

 cavity of A. canina. 



Distribution. Coast of Bohuslan (Thorell). 



