1909.] R. E. lyi^OYD : Deep-Sea Fish caught by the " Investigator." 165 



borders, if prolonged, would meet in front at an angle of 40°. The preorbital pro- 

 cesses therefore appear to converge. The length of each labial tentacle is equal to 

 the width of the mouth. 



The osseous plates between the ventral fins are unusually thick. The greatest 

 length of each anterior ventral plate is equal to the greatest breadth of both com- 

 bined. The greatest length of the posterior ventral plates is half that of the anterior 

 ones. The greatest length, in both cases, is to one side of the middle line. A quad- 

 rangular portion of the posterior plates fits into a corresponding hiatus in the anterior 

 plates. Throughout the length of the body, on either side, there are four rows of 

 plates, each with a large spine shaped somewhat like a rose- thorn, their points curv- 

 ing backwards. The lowest row is much less conspicuous than the others. 



There are large postorbital, occipital, post-temporal, and two opercular spines, a 

 small upper and a large lower one, on either side. There is one small median spine, 

 an orbit's length in front of the orbits. 



The greatest height is one-fifth the total length. Total length of the single speci- 

 men 6| inches ; greatest length of the head 3 inches. 



Colour. — Reddish yellow, pectorals grey, dorsals tipped with black. 



Habitat.— Gulf of Aden, 130 fathoms, Station 360. Registered No. ^^^^. 



Division JUGULARES. 



Family ZOARCID^. 



Diplacanthopoma squamiceps , Lloyd. 



Rec. Ind. Mus., vol. i, part i, p. 10 (1907); Illustr. Zool. " Investigator," Fishes, 

 pi. xHi, fig. (1908). 



Corresponds with the generic definition in the following respects : — the form and 

 arrangement of the fins, of the teeth and the gills, in the number of the branchioste- 

 gals (8), in the absence of pseudobranchise and pyloric caeca, in the obscurity of the 

 lateral line, and in the presence of radiating spines on the opercles. It differs from 

 all known species in this important respect : — there are scales on the head as far for- 

 ward as the posterior limit of the eyes and on the opercles and sides of the head as 

 far forward as a line dropped vertically from the posterior border of the eyes. The 

 head is much depressed and the eyes are close together and look upwards to a great 

 extent, being separated by less than their diameter ; this gives the head a very different 

 appearance from that of the other three known Indian species of the genus, in all of 

 which the eyes are separated by about i| times their diameter. 



There are deep mucus pits on the head and in a semicircle below the orbits. 



There are no pseudobranchise, but in the position of these organs there are two 

 very short and slender filaments which are vestiges of this organ. I find that the 

 type specimens of D. riversandersoni and D. raniceps have precisely similar vestiges. 

 This seems to be a strong argument for including this new species under the genus 

 Diplacanthopoma. 



