DR. RICHARDSON'S DESCRIPTION OF AUSTRALIAN FISH. 81 



Inches. Lines. 

 Diameter of stomach 7 



Diameter of pyloric branch at its origin 2^ 



Diameter of ditto at its termination in the gut IJ 



Aplodactylus arctidens, Tasmanian Aplodactylus. — Ap. arctidens, Zool. Proceed., 



June 2.5, 1R39. 



Ap. dentibus tricuspidatis, supeiioribus in serie octupUci, inferioribus in serie quintu- 



plici ordinatis ; cacis pylori quatuor. 

 Radii.— Br. 6 - 6 ; P. 9 et VI. ; V. 1|5 ; D. 16]- 1|17 ; A. 38 ; C. 16f. 



The labels which had been attached to the two specimens of this fish in the collectioa 

 had dropped off, so that Mr. Lempriere's list gives us no certain information of its habits ; 

 but it is evidently a littoral fish, the whole of its intestines being filled with large pieces 

 of a thin membranous sea- weed, resembling or identical with Ulva umhiltcali^, mixed with 

 some balls of confervje, and also a few shells with the animals in them undigested. A 

 fleshy substance, like the stem of a sea-anemone {Actinia), was found mixed with the 

 weed in the rectum. 



The Aplodactylus arctidens is a second species of the genus, the previously known 

 one ipunctatus) being an inhabitant of the seas of Chili. It resembles the latter very 

 closely in external form, except that the ventral and anal fins are much smaller, the 

 pectoral ones proportionally larger, and the caudal nearly even at the end. The den- 

 tition also differs in the interior rows on both jaws being formed like the exterior ones, 

 though much smaller'. The teeth are narrow, thin, flexible, and festooned at their 

 summit into three lobes, the lateral lobes being shortest and smallest. They form eight 

 or nine densely crowded rows on the upper jaw, and about seven on the lower one, so 

 graduated as to render the dental surface concave. The teeth of the interior row, though 

 scarcely visible through the gum, are shaped just like the others : all are a little curved 

 backwards. There is a small patch of fine villiform teeth on the chevron of the vomer, 

 and a minute corner of the patch extends on each side to the palate bone. The cheek, 

 operculum and suboperculum are protected by small scales, as in punctatus ; but there 

 is a broad, naked, posterior margin to the operculum, including a nearly equal breadth 

 of bone and membrane : the limbs of the preoperculum, the interoperculum, anterior 

 orbitar, circumference of the eye and the whole top of the head are naked. The scales 

 of the cheek mn up towards the supra- scapular, and there is a small scattered patch of 

 scales on that bone. A narrow smooth groove separates a scaly fillet, which covers the 

 base of the dorsal from the integuments of the back. 



' The following account of the teeth of Aplodactylus punctatus is given in the ' Histoirc des Poissons ': — " Les 

 dents sont dispose'es sur trois rang^es 3 la machoire superieure et sur deujc il Vittferieure; elles sont aplaties et (mt 

 leur bords arrondis et dentelCs en petlts /estortu ; elles sont tr'fs semblables a celles des Cri'nidens ; on en compte ijxia- 

 torze de chaque c6te tl la machoire superieure el treize a finferieure. Derrtcre ces rangf'es antericures il y a des 

 petites dents grenues sur une band ^troite a chaque machoire et sur le chevron du vomer. Lespalatins n'en oni point." 

 VOL. III. — PART I. M 



