548 '* THETIS " aCIENTIPIC RESULTS. 



covered with a fine, granular pavement. Each jaw carries about 

 a dozen more or less spiniforra oral papillae and teeth. Genital 

 slits minute. First pair of arm-pores without tentacle-scales, but 

 all subsequent pores are guarded by a series of four to seven, very 

 small, peg-like tentacle-scales (arm-spines), of nearly equal size. 

 Colour, very light brown or dirty whitish, prettily annulated from 

 tip of arm to centre of disc with bright brown ; lower surface of 

 arms brown. 



One specimen from Station 48. Off Wollongong, 55-56 

 fathoms; sand and mud to rock. 



The occurrence of a species of Astroporjia in Australian waters 

 may be considered one of the noteworthy discoveries made by the 

 " Thetis," for the two species ])reviously known are exclusively 

 West Indian. The Australian species resembles A. aimulata,. 

 Orst. and Ltk., very closely, but is easily distinguished by the fact 

 that the half-circles of hook-bearing granules are broader and more 

 flattened and carry less conspicuous granules and hooks, particu- 

 larly at base of arms ; thus, in annulata there are only two or 

 three series of granules in each half-circle and at base of arm 

 there is usually only a single, conspicuous series, while in 

 australiensis there are four or five such series. The colouration of. 

 the two species is remarkably similar. 



ASTR0THR0MBUS,"9 gen. nov. 



Disc covered by a very irregular, rough pavement of granules; 

 and plates of very diverse sizes, among which one fails to find any 

 definite indications of radial shields, though the largest plates are 

 at the bases of the arms, and may even be arranged in a more or 

 less noticeable pair. The arms are simple, capable of coiling 

 vertically, with the side arm-plates continued upwards in double 

 lines of close-set nodules, homologous with upper arm-plates, and 

 bearing minute hooks. Tentacle-scales, several, short and rough, 

 at tip. Jaw with a very few sharp teeth or papillae at apex. 

 Two genital openings in each inter brachial space. 



Type-species, the following. 



ASTROTHROMBUS RUGOSUS,^^ sp. nov. 



(Plate liv, fig. 3.) 



Diameter of disc, 7 mm.; length of arm, 30 (?) mm. Disa 

 covered with a very irregular pavement of granules of diverse 



aoTpov=a. &ta,r + dp6ix^os=a, lump, symphonious with its generic allies,.. 

 and in reference to the rough disc. 



^° rugosus=rough, in reference to the irregular covering of the disc. 



