On nondescri'pt Bones in the Skull of Osseous Fishes. 397 



not exist ; for though I myself have not been fso fortunate as to 

 find any specimens of ichneumon in their nests, one has been 

 seen in them by Mr. Denison in several instances, and ob- 

 served in all the stages of its growth. It is described by 

 him as a fly, as large, or nearly as large, as the wasp itself ; 

 the head and fore part of the body black, the abdomen yellow, 

 with a dark streak down the back ; legs and wings black ; 

 upper wings dusky. This fly {RhijJiphorus) deposits its egg 

 upon the grub of the wasp at the moment it assumes the pupa 

 {i. e. spins or covers itself in the cell) ; as soon as the egg is 

 hatched, it devours the grub of the wasp entirely, and itself 

 assumes the pupa- and imago-form in the cell of the wasp." 



XL VII. — On certain nondescri])t Bones in the Skull of Osseous 

 Fishes. By Geoege Gullivee, F.R.S. 



Aftee the much ado of late years about the osteology of the 

 fish's head, it may seem surprising to announce undescribed 

 cranial bones or ossicles in these animals. But that there are 

 such pieces of the skull will probably be admitted by anato- 

 mists who may pay attention to the question. 



A relation of the means by which these bones became known 

 to me will show how and where they may be found ; and this 

 is the object of the present communication. 



In separating and trying to put together again that seg- 

 ment of the fish's skull known as the frontal vertebra or 

 prosencephalic arch, I have always found supernumerary 

 bones — that is to say, besides all those usually given as com- 

 posing that arch, a pair of neat ossicles, each of them thin, 

 cup-shaped and subconical, somewhat triangular or subpyra- 

 midal, and measuring, in large codfish, about three-fourths of 

 an inch across the base of the cone and in depth. The apex 

 of each of the bones is rather obtusely pointed ; and either of 

 them, with its small end most deeply placed, occurs regularly, 

 sunk into a pit, and easily separable therefrom in the boiled 

 fish's head, at the hind part of each postfrontal. 



The Avoodcut represents, of the natural size, 

 one of these postfrontal ossicles, or expostf-on- 

 tals, from a small codfish. 



After a diligent search through the English 

 books of comparative anatomy, I have been un- 

 able to discover any notice of the bones in ques- 

 tion. And as they had so often puzzled me, I took them to 

 London, on the 6th of August last, when and where they 

 were compared with the admirable preparations of the skele- 



