TKACIIYl'TKUID.K. 



321 



Ja'tken has specified certain osteological rlistinotions 

 hetweeii tlie genera Begaleens and 'f'rachi/pfenis, chiefi_y 

 affecting tlie general structure of the skeleton. In Ik-f/a- 

 IccKs, which is usualh" of coiisideralih' greatei' dimen- 

 sions, in spite of this the skeleton is nuich looser, a 

 circumstance which is, however, consistent with the fact 

 that Rcgaleciis is a deep-sea genus of a still more marked 

 description. As we have seen above, there is no lack of 

 characters to distinguish between the two genera; but on 

 the other hand, it cannot be denied that they are very 

 closely related to each other, especially if the changes 

 of development be taken into consideration. 



The earliest stages liave hitlicrdi been almost unknown; but by 

 the kindness of Professor I.ECut: \vc aic liere enabled to give some 



damaged and indistinct. The depth of the body, whicli is eoiisider- 

 ably less than the length of the head, gradually decreases from the 

 occiput to the very end of the tail, which is furnished with a long, 

 though damaged and broken, caudal tin. This fin (fig. 86) consists 

 of seven simple and uiiartiiulated rays, the four lower (pnes articulating 

 with the hypural bones, which are directed straight backwards, and 

 tlie three upper with the end of the urostyle. The second and third 

 rays from the top, however, are rudimentary, and the fin is thus di- 

 vided into two parts, with one ray at the top entirely separated, to 

 all appearance, from the lowest four rays by the interval referred to. 

 All the rays are broken, but the pieces of the middle ray are still 

 united by a thin filament, and end in an extremely fine filiform tip. 

 This ray, as well as the uppermost and lowest rays, is also rough 

 at the sides with two rows of spines pointing in opposite directions, 

 a character which reminds us of the preceding germs. When perfect, 

 this ray seems to have been half as long again as the head. An 

 essential distinction between this genus and 7'rachi/pterii)} may thus 

 be drawn frum the circumstance that in the former tlie rudimentarv 



Fig. 80. Caudal fin of a Regaleciis jladius 36 cm. long, from Messina. 



ilelails with regard to a specimen of Jieijalectis gladius, 36 cm. long, 

 which he received at Messina. 



The head is perfect in the essential points, and shows that ex- 

 tensive elongation of the preoperculum, the interoperculum and the 

 hyomandibular, together with the quadrate bone, downwards and for- 

 wards to a point in front of the perpendicular from the anterior 

 margin of the eye by a distance equal to the longitudinal diameter 

 of the ej'c, which sets the articulation of the lower jaw in such 

 a position that the lower margin of the latter is perpendicular, when 

 the month is closed, and thus forms the front of the head. The 

 jaw-teeth are wanting. The operculum is triangular, with the hind 

 corner, which forms the end of the head, obtusely rounded. Beneath its 

 inferior side lies the suboperculum, which is of fairly uniform breadth, 

 but somewhat broader behind than in front. Only the anterior part 

 of the occipital fin is persistent, i. c. the first, strongest ray and the 

 next four. The tips of those rays are broken off short, but their 

 length is still about '/s greater than that of the head. Of the rays 

 behind these there is no trace, in front of the dorsal fin proper, which 

 b3gins in a line with the middle of the operculum. Each of the 

 ventral fins contains only one ray, even this being broken, but in the 

 left fin about equal in length to the head. The pectoral fins are 



rays are situated at tlie top of the caudal fin, in the latter at the 

 bottom. In this circumstance we may perhaps find a partial expla- 

 nation of the more general retention of the caudal fin in Trwhyptevus 

 and its almost invariable loss in Regalecus. The other ditferences, 

 however, atfect only the degree and not the direction of the deve- 

 li>pment. 



We thus retain the genus BcgalecKS, but only as 

 the expression of an intermediate stage between Lo- 

 pliotes and Tradn/pferKS. 



It is perhaps a matter of doubt \\hether more 

 than one species is known from the Atlantic, the Medi- 

 terranean, the East Indies" and Australia: but it is 

 apparently certain that only one species of this genus 

 belongs to the north of the Atlantic and the Scandi- 

 navian fauna, that same species which on many, if not 

 all, occasions has given rise to the mysterious accounts 

 of the "great sea -serpent'. 



" It seems hardly probable that Regaleciis Russellu from Vizagapatam is a distinct species. It has never reappeared since 1788, and 

 there is no specimen of it in existence. Even Sh.\w (Gen. Zool., vol. IX. p. 195, tab. 28) regarded Russell's Gymnetnis as an early stage 

 of the development of Regaleciis glesne. 



Scandinavian Fishes. 



41 



