VI. On the Structure of Trachypterus areticus (the Northern Ribbon-Fish ). 
By ALEXANDER MeEgx, University College, Dundee. 
In the year 1872 a very splendid specimen of the Ribbon-Fish came ashore near the 
town of Montrose. The specimen—nearly six feet long—was partially described 
and figured by Dr Howpsn, of Montrose,* and served, moreover, as the subject for 
a well-known figure in Day’s “ British Fishes.” Unfortunately, the specimen was 
neglected, and having fallen to pieces, was sent us, that, if possible, it might yet be 
repaired and set up as a skeleton. The task was becoming hopelessly difficult, when 
we received, by the great kindness of Professor Liitken, of Copenhagen, two smaller 
examples of the same fish, in sufficiently good preservation for osteological research, 
and for the examination of a few of the viscera. From one of these the following 
results have been chiefly drawn. The dimensions of this specimen were as follows :— 
Length, 33 feet; greatest depth, 64 inches (in region of anus). The thickness 
varies from 1? inches in the cranial region, to an extreme tenuity between the inter- 
spinous bones. 
No minute account of the osteology of Trachypterus has been published 
heretofore, but Professor T. J. Parker’s monograph on Regalecus argenteus,+ has 
furnished us with a basis for the following description, and, indeed, the recent 
thorough examination of this closely-allied genus helped to add interest to a closer 
study of our Northern Ribbon-Fish. It will be seen that numerous minor structural 
differences exist between these two much modified and in general very similar forms. 
The external characters of the fish are sufficiently well known. Such points, specific 
in general, as remain uncertain or deserve particular attention, have been discussed 
by LurKen,} Emery,§ and others: on these points, for instance—the character of 
the ventral fins, the anterior portion of the dorsal or nuchal fin, etc., our specimens 
throw no new light. And we are accordingly confined to an anatomical description, 
principally of the skeleton. 
The Skull. (Plate 1.) 
The skull of Trachypterus is remarkably modified, on the same lines as in 
- Regalecus, in consequence of the great lateral compression of the whole fish. We 
* Rep. Montrose Nat. Hist. and Antig. Soc., 1872. 
+ T.Z.S., Vol. XIL, Pt. I., 1886. 
¢C. Liven. Trachypterus arcticus og Gymnetrus Banksii. Vidensk. Meddel. fra den naturh. Foren. 
i Kjobenhaen. 1881. Nogle Bemerkninger om Vaagmeren. Oversigt over K. D. Vidensk. Selsk. 
Forhandl. 1882. 
§ Emery. Contribuzioni al? Ittiologia. Atti d. r. Acad. d. Lincei, Roma. 1880. 
