510 FISHES. 



The three species known of this genus are found in the 

 tropical Indo-Pacific. Their body is so thin that it has the 

 appearance of being artificially compressed between two 

 sheets of paper; it is semi-transparent, especially in the 

 region of the air-bladder. The structure of the vertebral 

 column is extremely singular and unique among Acanthop- 

 terygians. The abdominal portion is more than four times 

 as long as the caudal; nevertheless it is composed of only 

 six vertebrae, whilst the latter consists of fourteen. The 

 abdominal vertebraa are extremely slender, the third alone 

 being nearly as long as the whole caudal portion ; they have 

 a slight ridge superiorly and inferiorly, and on each side ; the 

 whole portion lying in the uppermost concavity of the dorsal 

 cuirass. The caudal vertebrae are extremely short, and the 

 strength of their neural and hsemal spines is in proportion to 

 their size. The dorsal cuirass is not a dermal production, 

 but formed by modified parts of the endoskeleton ; its com- 

 position, the number and condition of its single parts, and, 

 finally, the first dorsal spine, which in A. punciulata is so 

 singularly attached to it, favour this opinion. The plates, 

 which occupy the vertebral line, would correspond to the 

 neural spines, and the lateral plates on which the ribs are 

 suspended to the parapophyses. Aviphisih may be con- 

 sidered as a Chelonian form among fishes. 



POUETEENTH DIVISION — AOANTHOPTEEYGII GOBIESOCIFOEMES. 



No spinous dorsal; the soft and the anal short or of 

 moderate length, situated on the tail; ventral fins subjugular, 

 with an adhesive apparatus between them. Body naked. 



These fishes are well characterised by their single dorsal 

 fin, and by their adhesive ventral apparatus, which has only 

 an external similarity to the organ observed in Cyclopterus 

 and Idparis; its structure is typically different from it. 



