BOREAL 1'i;aki,-sii)i:. 



93? 



species, but arc curved in ii .sabre-lii<e fasiiioii tlirough- 

 out their length, and their suppieinentary bone, which 

 is elliptical behind, projects in front in a tip that ex- 

 tends to a line with the anterior part of the preorbital 

 bone. Their median Ijrcndtli is ratlier more than Vs 

 of tiieir length, wiiich is equal to that of the lower 

 jaw, and less than 15 % of that of tlie bodj' or than 

 16 % of the Ictigtii to tlic middle (if the base of the 

 caudal tin. In this last relation we iiave a character, 

 constant to the best of our knowledge, to distinguish 

 this form from tiic Mediterranean MauroUcits ame.tlujs- 

 tino-pi(iict(iiiis, which is otherwise deceptively like 31. 

 MiiUrii. Tiie liranches of tlie lower jaw are deep, but 

 have an arcuate U))per margin; and the symphysis is 

 shallower than in Aiy/ijropeleciis Olfarsii and has a 

 feeblv developed chin-j)rotuberance, which liowever pro- 

 jects distinctly, when the mouth is closed, beyond the 

 tip of tlie snout". As in Arf/i/ropch'cufi Olfersii, a 

 sharp ridge runs along the outside of each half of the 

 lower jaw, parallel to the thin inferior margin. The 

 liraiiches of the lower jaw approach rather near to 

 uarli other at the inferior margin behind; but in front 

 (behind the symphysis) the space between them widens 

 into a clavate mentum (chin-space). The feeble den- 

 tition of the mouth consists of small, pointed teeth, 

 set in a single row and of uniform size, on the inter- 

 maxillaries, on the hind (free) part of the lower edge 

 of the maxillaries, on the upper edge of the lower jaw, 

 as far as it is free when the mouth is open, and in 

 an arcuate transverse row on the head of the vomer. 

 There is no tongue; Init tlie anterioi' (lower) part of 

 the basihyoid bones forms a transversely-set rim, rising 

 within the mouth like a tongue. The upper palatal 

 fold is extremely narrow, the lower better developed. 

 The psendobranchia' ai-e rather large, but consist of 

 only 'J or 10 transversely-set, tilamentous lainelhe. 

 The gill-rakers are set in one row, pointed, rather 

 long, and so dense that they number about 30 on the 

 front of the lirst branchial arch. The tirst gill- slit is 

 long, the others rapidly decrease in length. The outer 

 gill-openings are large in this species too, the two 

 branchiostegal membranes being hardly at all coalescent. 

 Above they extend to a level with the upper margin 

 of the eve, below to a line with the anterior extremity 



of the pref)rbitMl bones. Tlie branciiiostegal rays are 

 10, the first <'xtremel)' small, the others slender, ex- 

 cept the last (uppermost), which is broad and sabre- 

 shaped. Among the thin bones of the opercular appa- 

 ratus both tiie operculum and suboperculum ai-e (pia- 

 drilateral, rectangular, the former being rather more 

 than twice as large (deep) as the latter, but with the 

 upper posterior angle rounded. In the lower margin 

 of the suboperculum there is a rounded indentation. 

 The interoperculum is more oblong, growing narrower 

 in front, and lies along the lower arm of the pre- 

 opercidum. The preoperculum resembles a somewhat 

 o])en (obtuse-angled) carpenter's stpiare, witii lioth arms 

 of nearly ecpial length. 



The dorsal tin is trapezoidal, with the upper pos- 

 terior margin rapidly sloping. It begins at a distance 

 from the tip of the snout measuring about 55 — 48 % 

 of the length of the body. The length of its base is 

 al)out 9 — 7^2 %, its height in front about lOVg — 12 %, 

 of the length of the body. The adipose tin, situated 

 above the posterior part of the anal tin, is long and 

 low, as in Argi/ropeleciis Olfersii. The anal fin is much 

 longer than the dorsal, but so deeply incised at the 

 margin that its anterior part is almost similar to the 

 latter fin, though much lower, while its posterior part 

 is very lo^v and of uniform height, only the last rays 

 being slightly prolongated. Its distance from the tip 

 of the snout is about 63 — 60 %, its base about 18',\. 

 — 20 ?'6, and its greatest height about ' \„ of the length 

 of the body. The caudal fin is forked, though not so 

 deeply as in Arciyropelecus Olfersii; its middle rays 

 occupy about 7 — 8 % of the length of the body'. At 

 the upper margin we have found 8 supporting rays, at 

 the lower 5. The pectoral fins ai-e bluntly pointed, 

 semiov-al. Their length is about 16 — 14 % of that of 

 the body. The ventral fins are oi' almost the same 

 shape, but much shorter, their length being about 9 — 

 10 % of that of the body, and only slighth' greater 

 than or even ecjual to the diameter of the eye. They 

 are set at a distance from the tip of the snout measur- 

 ing about .)2' 2 — oO'/g ?o of the length of the body, 

 sometimes a little in front of, sometimes behind the 

 perpendicular from the beginning of the dorsal fin. 

 The preabdoniinal length is about 30 (31\/,,— 29'/.,) % 



" Both the maxillariis and thi- lower jaw are so tlihi and transjiarent that the wh<ilc of tlie former and tin- iippir |uist<-ri(.r part of 

 tlie latter are invisible in v. Wrights tisfuri'. 



' In V. WRinin's ligun-. which evidently represents a fresh and perfect spe<inien, the caudnl fin is much less forked than in our 

 Bpecimens. 



