TRACHICHTHYS PRETIOSUS. 63 



On opening the abdomen^ the sides or parietes of which are, as in Beryx, pe- 

 cuharly thin, and tending rapidly to decomposition, the whole peritonetim and 

 stomach, like the tongue and inside of the gullet, mouth, and branchial opening, 

 are found to be deep shining black. The liver is of middle size ; the gall-bladder 

 large ; the stomach small ; and the intestine small and short. The cceca are 

 numerous, but slender, short, and inconspicuous ; and like the intestine, pale or 

 yellowish. The air-bladder was large, simple, ovoid, blunt at both ends, without 

 any communication with the oesoj)hagus, and pearly-white. MM. Cuvier and 

 Valenciennes speak of it as small. In this example, however, measuring only 

 eight inches and three eighths in length, it was an inch long or more. The 

 ovaria were distinct and rather large or turgid, but the eggs were very small and 

 imperfect. The abdominal cavity is very large ; but, as in Beryx, the mass of 

 viscera is small. 



These characters, it may be observed, corroborate completely the affi- 

 nity with Beryx of Trachichthys. 



On clearing away the membranes or integuments about the head, there is found 

 to be externally no fleshy muscle, except at the small scaly patch behind the 

 ends of the maxillaries ; i. e. below the suborbitary : and the two middle trans- 

 verse dissepiments of the preopercular border, like those of the two elliptic cells 

 over the eyes, are found to be spurious or merely membranous. The uppermost 

 and lowest dissepiments, however, of the preopercular border are bony ; and the 

 lowest, especially, is much dilated or broadly winged, and granulato-striate ver- 

 tically. 



The radiating stride of the opercle are very strong, and rather elevated ribs 

 than striae. They are beautifully and finely pectinato-denticulate, like all the 

 crests and ridges on the top of the head. 



The superscapulary is of the usvial structure, viz. a large elliptic plate, with the 

 hinder edge finely toothed ; forming the base of the large elliptic cell before 

 described close above the origin of the lateral line, and bordered along its lower 

 edge by a strong rough ridge ending in a sharp spine, directed a little obliquely 

 downwards, or along the lateral line. Over the middle of this superscapulary cell 

 lies the dilated ridge or spine which MM. Cuvier and Valenciennes have called 

 mastoidal ; but which belongs rather to the system designated by these authors, 

 (Hist. i. 338), after M. Bakker supertemporal. It is loose and moveable, as if 

 merely dermal ; and is quite distinct from the true mastoid, although joining on to 

 it behind, outside the junction of the superscapulary with the same.* 



* Since the above was printed, I have been favoured by Professor Owen with the following 

 confirmation of this view : accompanied with such profound and original observations on the 

 whole subjest of these long misunderstood external ossicles in Fishes, that I must solicit his indul- 

 gence for the liberty of enriching these pages by their transcription. In a letter dated " Royal 

 College of Surgeons, April 8th 1840," he observes, " After a careful comparison of your skeleton of 

 the TracJiichihi/s with those of other fishes in the Hunterian Collection, I have come to your con- 

 clusion, viz. that the bone in question represents the supplemental series constituting the supra- 

 temporal chain. It undoubtedly intervenes between the Siiprascajmlar of Cuvier and the mastoid, 

 as correctly marked by you. It is a part of the same system of bones with the suborbital chain ; 

 and like them supports the vertical ridge with the expanded granular peripheral plate. 



" The skeleton of fishes includes two sj^stems of ossified parts : one peripheral or dermal ; the 

 otlier central. The latter is the tj-pical skeleton of the Vertebrates ; the former a part of the pre- 

 vailing skeleton of the Invertebrates : and it is the intercalation of a remnant of the dermo-skeleton 

 with the true vertebrate endo-skeleton that gives rise to such apparent complexity in the osseous 



