9-4 Neio Fishes from the South-west Coast of Ireland. 



several short branches ; behind this a tuft of very slender 

 filaments, followed by a luminous organ in the form of a 

 backwardly directed truncated cone, and posteriorly a rather 

 stout filament a little longer than the clavate head of the 

 tentacle (the whole apparatus resembling that of 0. esch- 

 rtchtii). Pectoral above and in front of gill-opening with 

 14 feeble rays, the longest about a quarter as long as the 

 head. Caudal with 8 rays, the longest more than half as 

 long as head. 



Coloration dense black, fin-membranes and tip of tentacle 

 with its appendages colourless. Stalk of tentacle (in present 

 condition of specimen and perhaps normally) pale. 



Loc. S.R. 497, 10. ix. 07, 51° 2' N., 11° 36' W., 775-795 

 fath. j ooze, trawl. 



Dimensions of Type. 



mm. 

 Total length, including lower jaw aud caudal tin . . 89 



„ without caudal hn 67 



Length of head (tip of snout to hind edge of gill- 

 opening) 41 



Tip of snout to base of pectoral fin-rays 36 



„ „ eye (between verticals) ca. 12 



„ „ angle of jaw (between verticals) . . ca. 19 



Horizontal diameter of eye ca. 3 



Breadth between tips of frontal spines 20 



,, „ mandibular spines * 34 



Distance from tip of frontal to tip of mandibular 



spine (actual) 31 



Greatest height (a little anterior to gill-opening) . . 47 

 Height of caudal peduncle 10 



It is with some hesitation that we treat our specimen as 

 specifically distinct from 0. eschrichtii, Liitk. (1871), which 

 is at present known from a single specimen, about 8 inches 

 long, taken oflf Greenland. The two species agree in all 

 essential particulars, and the only obvious differences lie in 

 the lengths of their respective tentacles (that of 0. eschrichtii 

 being less than half as long as the head and that of 0. mega- 

 ceros longer than the head) and in the reduction of the second 

 dorsal spine (which in 0. eschrichtii is as long as the 

 tentacle) to a mere vestige in 0. megaceros. It is possible 

 that these difi'erences may be of a developmental or sexual 

 nature only, as the type of 0. megaceros is less than half the 

 length of' that of 0. eschrichtii. We have, however, no 

 evidence of any reduction in length of the tentacle of Geratiids 

 with growth, and the tentacle of 0. megaceros is actually 

 about a third as long again as that of 0. eschrichtii. More- 

 over, in the very small known specimens of 0. niger^ Brauer, 



* This dimension can be reduced by slight pressure. 



