56 



whole side of the head : whence the name of this family of fishes, Sclerogenidce, or ' Hard- 

 cheeked.' The carpal bones are unusually large, and the first three digital rays of the pec- 

 torals are thicker than the rest, from which they are detached : they are jointed and flexible, 

 and are supplied in the recent fish with nerves, which come off from a special gauglionic 

 swelling of the dorsal or sensory columns of the spinal cord : the summits of the interneural 

 spines are expanded into a series of horizontal, subquadrate, bony plates. The number of 

 abdominal vertebrae is 14 ; that of the caudal vertebrae is 21 : total, 35. 



Purchased. 



208. A dried specimen of the flying Gurnard (Trigla volitans, Linn. ; Dactylopterus 



communis, Cuv.). 



The posterior prolongation of the long and pointed bony processes from the postfrontal and 

 mastoid regions of the skull, the large suborbital dermal bones, and the strong serrated spines 

 of the preoperculars, are worthy of notice. The six short anterior articulated rays of the 

 pectoral are united by a membrane through four-fifths of their extent, and are detached from 

 the rest of the pectorals : this forms on each side an enormously expanded parachute, capable 

 of sustaining and carrying the fish through a short flight : the posterior portion of the 

 elongated and divided rays of this part of the pectoral are strongest on the under part of the 

 parachute : they are finely jointed at their extremities. 



Purchased. 



209. The skeleton of a species of Pristipoma. 



It shows well the serrated margin of the preopercular piece of the gill-cover, a character 

 which is signified by the generic name. The outer surface of the preopercular bone, together 

 with that of the suborbital bones, of the supratemporal and the frontal bones, is excavated or 

 sculptured by a bold reticulate pattern. Both the frontal and superoccipital bones are re- 

 markable for the thickness and density of their osseous texture, which resembles ivory. The 

 third pair of ribs is unusually broad. The anterior dermal spines of the dorsal and anal fins 

 are unusually strong. The number of abdominal vertebrae is 10 ; that of the caudal vertebrae, 

 17; = 27. The skeleton was brought from the Cape of Good Hope. 



Purchased. 



210. The skeleton of a Scisenoid fish (Trachichthys preliosus, Lowe; Hoplostethus 



mediterraneus, Cuv. & Val.). 



The external surface of the cranium is remarkable for the bold reticulate pattern in which 

 it is excavated or, as it were, sculptured : this character is particularly manifested in the 

 large suborbital scale-bones, from the fore-part of which a bony bridge of the same character 

 spans across the united nasal, prefrontal and vomerine bones. The frontal crest bifurcates 

 and diverges posteriorly : the occipital crest is simple ; it is joined to the extremities of the 

 divided frontal crest by two thin plates of bone resembling semilunar valves ; but the chief 

 peculiarity in the skull of this rare fish is the large ' bulla ossea ' or basicranial cavity formed 

 by the enormous expansion of the basioccipital and basisphenoid bones. The ceratohyal is 



