FISHES OF THE FAMILY SIGANID^. 21 5 



There are two basibranchials ; the hypobranchials of the fourth 

 arch and the pharyngobranchials of the first are absent. There 

 are three pharyngobranchials present on each side, each a thin 

 concavo-convex plate, shaped like a clam shell, and bearing along 

 its lower edge a single row of long, slender, comb-like teeth. A 

 second, less complete row is situated towards the convex center 

 of the plate, though on the first plate the second row is repre- 

 sented by a single tooth. Similar teeth are arranged in four or 

 five " combs " placed obliquely across each slender lower pharyn- 

 geal. A third or more of the band of gill filaments of the first 

 arch (and a decreasing portion of it on the succeeding arches), 

 is free from the arch above its angle at the upper end of the 

 ceratobranchial, and rises upward on a cartilaginous base at each 

 side of the cranium in a cavity behind the eye. 



The hyoid arch is in no way peculiar in form or arrangement 

 of its elements, except that the paired hypohyals are larger than 

 usual ; a small glossohyal is present. 



The vertebrae number as follows : thoracic io + caudal 12 + 

 hypural = 23. 



The first vertebra has a wing of thin lace-like bone developed 

 outward and downward from the side of its neural arch to which 

 the first epipleural is attached. The parapophyses are scarcely 

 developed, but their small representatives are of about the same 

 size on all of the vertebras. The ribs are attached to the centrae 

 of the vertebrae with the anterior edges of their bases fastened 

 closely against the parapophyses. The epipleurals posterior to 

 the first are attached to the ribs at some distance from the verte- 

 brae. The spine bearing interspinous bones are somewhat wider 

 than the ray bearing ones. They expand laterally at the bases 

 of the spines, making a row of bony plates, which are evident 

 through the skin of the entire fish. The haemal, neural, inter- 

 haemal, and interneural all have a thin laminae of bone developed 

 backwards from their posterior edges. A long, strong process 

 extends forward from the first interhaemal towards the pelvic girdle 

 and forms a sharp abdominal ridge. A sharp spine projects for- 

 ward from the first interneural at the base of the first dorsal spine 

 and pierces the skin at the nape. The supplementary caudal rays 

 are attached to the backward extending spinous processes of 

 one or two vertebrae anterior to the hypural. 



