458 Prof. Reid on the Vogtnarus Islandicus. 



g^ths of an inch^ and the thickest part of the body where the 

 viscera were placed measured only about 1 inch. The thickness 

 of the most muscular part of the body immediately behind the 

 gills and a little above the vertebral column^ measured somewhat 

 more than an inch. 



In this, as in the specimen of Trachypterus vogmarus described 

 by Professor Reinhardt, the height of the sword-blade-shaped 

 body was the same or nearly the same for more than one half of 

 its length; while in the specimens of Trachypterus falx and 

 T. iris described by Valenciennes, the greatest height of the 

 body was at or near the occiput, from which it gradually tapered 

 towards the tail. 



The lateral line of the body at its commencement immediately 

 behind the operculum was nearer the upper than the lower edge 

 of the body, but it began immediately to descend, and continued 

 its course backwards to the tail, running nearer the lower than 

 the upper edge. The lateral line immediately behind the gills, 

 where the height of the body was 8 inches, was placed 3| inches 

 from the upper edge ; and where the height of the body was 1 1 

 inches, it was 4^ inches from the lower edge. 



It was not easy to reckon exactly the number of the dorsal 

 rays, but I counted 176. The length of the longest dorsal ray 

 was 4i inches. Only six rays were left in the caudal fin, and 

 the longest of these was 8^ inches. There were ten rays in each 

 pectoral fin, and seven of these were considerably longer than the 

 other three. The longest were from the second to the seventh, 

 reckoning from before backwards. The length of the pectoral 

 fin was 2^ inches and neai'ly 1 inch in breadth. 



A number of small cartilaginous tubercles presenting the ap- 

 pearance of warts was placed along its lower edge, and extended 

 upwards from that edge y^ths of an inch. The largest of these 

 were about g^ths of an inch in breadth, and less than y 2 th of an 

 inch in height. They became perceptibly smaller about 8 inches 

 from the end of the spinal column, and in the last 3 inches of the 

 lower edge were altogether absent. They were composed, as ascer- 

 tained by the microscope, of true cartilage. They were implanted 

 on a very strong band composed of dense fibrous tissue stretching 

 along the whole lower edge of the body. Along the line of junc- 

 tion of the cartilaginous and fibrous tissues, there was a thin layer 

 of fibro-cartilage. Fi*om the upper edge of this fibrous band a 

 fibrous lamina ran upwards and became continuous with the 

 fibrous lining membrane of the cavity of the abdomen, and behind 

 the abdomen it extended upwards along the mesial plane of the 

 body to the vertebral column. The lateral line is formed, as was 

 ascertained by microscopic examination, by a longitudinal band of 

 a peculiar tissue to be afterwards desci'ibed, which follows the 



