718 



APPENDIX. 



[No. VI. 



The nostrils are double, and situated immediately anterior to the eyes. The 

 anterior openings furnish small opercula, which exactly cover the posterior ones. 



The branchiostegous membranes are united to each other by a plicated skin conti- 

 nuous with the integuments of the abrinmen, hnt separater! from them by a trans- 

 verse shallow sulcus, and further distinguished by the absence of scales. There are 

 three broad flat rays in each membrane. 



The mouth is retractile, and placed under the snout, but when protuded extends a 

 little beyond it. When the lips are closed, the orifice of the mouth has a horse-shoe 

 shape, but when the jaws are extended it is nearly quadrangular — it admits the little 

 finger. The lips are attached to the intermaxillary and lower jaw-bones, and are 

 rough with large papillae, particularly the lower one, which expands into two pen- 

 dulous flaps. There are no cirrhi. 



The palate is lined by a thick gelatinous membrane of a light-red colour, which 

 rises anteriorly into two uvula-like eminences, forming the commencement of a 

 sulcus leading towards the pharynx. The sulcus is obliterated posteriorly by a large 

 pulpy cushion, against which the branchial arches may be pressed. This cushion 

 covers, or lines, a number of small bones and cartilages, which connect the superior 

 extremities of the branchial arches with each other ; united to it posteriorly there is a 

 cordiform substance of firm texture and white colour, which lines an irregular 

 cribriform osseous plate, that projects from the basilary process of the occipital bone. 

 Certain processes of the inferior pharyngeal bones, when pressed against the 

 callous cordiform substance just mentioned, may serve to comminute the tender 

 ^sects on which this fish preys. 



There are no teeth, but the processes of the inferior pharyngeal bones resemble 

 teeth in their form and office. These, to the number of thirty-six, project from the 

 bone on each side, in a pectinated manner, are compressed laterally, somewhat club- 

 shaped, a little worn on their summits, and gradually diminish in size, as they 

 recede from the maesial line. The pharyngeal bones themselves, which give origin 

 to these processes, are very strong, bear a resemblance in shape to the hoof of a 

 horse, are lined with the same membrane as the inner surfaces of the branchial 

 arches, and surround about two-thirds of the pharynx. The processes of these 

 bones are the only parts about the pharynx not thickly covered with membrane ; 

 their bodies are continuous with, and have the same structure as, the rest of the 

 bone ; but two or three of the largest have narrow crowns, approaching to enamel 

 in texture. There is no superior pharyngeal bone, unless the very irregular process 

 of the occipital bone may be so denominated. 



The branchial arches are furnished with a double row of thin, and rather rigid, 

 crests, having scolloped margins. These, when pressed against the soft cushion in 

 the roof of the mouth, must suffice to retain the food, until it undergoes that degree 

 of mastication which the apparatus in the pharynx is capable of giving. 



