SCIADO>iUS. 171 



preopercle are shorter, the uppermost being the longest of the three and the 

 lowest the least developed. The angle at the end of each lower jaw is a 

 spinelike prominence. Nape high, arched ; a slight concavity on the crown. 

 Snout massive, broad, more than twice as long as the eye, surmounted by a 

 pair of sharp horizontally extended spines, Plate F, fig. 3 a. Eye lateral, 

 small, less than half as long as the snout, less than one seventh as long as 

 the head, nearly one third as wide as the interorbital space. Mouth wide ; 

 the cleft slightly rising forwards ; maxillary nearly half as long as the head, 

 reaching a considerable distance farther back than the orbit ; lower jaws 

 siiorter, included. Teeth small, not very close together, in villiform bands 

 on jaws, vomer, and palatines. Nostrils lateral. Bones of the skull .soft, 

 with large mucous cavities. Gill openings Avide ; membranes not united, 

 free from the isthmus. Gill rakers short, slender; lamella) very short. No 

 pseudobranchite. Origin of the dorsal above the bases of the pectorals, pre- 

 ceded in the specimen described by a couple of rudimentary spines. Anal 

 origin below the eleventh or twelfth ray of the dorsal. A space at the cau- 

 dal separating it from dorsal and anal was probably traversed by membranes 

 uniting it with these fins. Ventral bases below the eye, fins each with two 

 slender filamentary rays, the longer of which reaches quite to the vent. 

 Vent below the middle of the pectoral fin. Existence of scales a matter of 

 some doubt. Lateral line not apparent. 



Top of the head to below the eye whitish ; mouth, chin and body 

 chamber black ; from the origins of dorsal and anal backward cloudy 

 brownish. 



The shape in this species is similar to that of A. annaius, the differences 

 appear in the branchiostegal rays, the ventrals, the scales and the lateral 

 line. 



Total length hardly more than three inches. 



SciADONUS gen. n. 



Compressed and elongate in form ; head massive, snout blunt. No eyes. 

 Gill membranes free from the isthmus. Gill lamelte very short. Branchi- 

 ostegal rays seven. Vertical fins united at their bases. Pectorals pedicel- 

 late, narrow, long. Ventrals filamentary, small, of a single ray, close 

 together, below the humeral symphysis. No cephalic spines. Opercles 



