55 



16. Notopterophorus papilio, Hesse. 



(PI. XXVII). 

 Notopterophorus papilio, Hesse, Ann. Scienc. Nat., ser. 5, Vol. 1, p. 338, PI. XI, figs. 1 13. 



Specific Characters. Female. Body comparatively more slender than in 

 the preceding species and generally more strongly curved, being moreover 

 highly distinguished by the extraordinary development of the wing-like ex- 

 pansions, which are very delicate, hyaline, and divided at the end into soft 

 threadlike processes. The number of these expansions is 6 in all, the 4 middle 

 ones being arranged in pairs on the 2nd and 3rd trunkal segments, the other 

 2 forming median plates issuing the one from the 1st trunkal segment, the 

 other from the end of the incubatory pouch. Both these median expansions 

 are somewhat spatulate in form and divided at the end into 3 threadlike pro- 

 cesses, whereas only 2 such processes occur on each of the paired expansions. 

 Structure of the caudal rami and of the several limbs almost exactly as in the 

 preceding species. 



Male of very small size, and exhibiting an appearance rather unlike that 

 in female, being wholly devoid of any dorsal expansions, and resembling in 

 shape the males of most other Doropygids. 



Body of female, in the living state, semipellucid, of a light yellowish gray 

 hue, with the ovarial tubes and the ripe ova dark fuscous in colour. 



Length of adult female attaining 4.30 mm.; that of male scarcely ex- 

 ceeding 1.20 mm. 



Remarks. The present species exhibits a most peculiar appearance by 

 the strongly prominent wing-like expansions surrounding the back of the body 

 and extending in different directions. Some variability of these expansions 

 may however be found to occur, and in younger specimens they are, as a rule, 

 much smaller than in fully adults, though always, unlike what is the case in 

 N. auritus and elongatus, distinctly divided at the end into well-marked thread- 

 like processes. 



Occurrence. I have only met with this remarkable form in a single 

 locality, viz., at Mold0en, west coast of Norway. It was found occasionally in 

 the branchial cavity of large specimens of Phallusia mentula. Most of the 

 specimens obtained were of the female sex; but on a closer examination of 

 the collected material, also some few male specimens were detected, one of 

 them still attached to the back of a young female by the aid of his rather 

 powerfully developed posterior antennae. 



Distribution. Coast of France (Hesse), British Isles (Brady). 



