78 Mr. A. Alcock on 



Laccadive Sea, 1200 fathoms, coral and Globigerina- 

 ooze. 



PONTASTER, Sladen. 



4. Pontaster mimicus, Sladen. 



Pontaster mimicns, Sladen, ' Challenger ' Asteroidea, p. 48, pi. \i. figs. 1 

 and 2, pi. vii. figs. 5 and 6. 



Laccadive Sea, 1000 fathoms, olive mud. 



5. Pontaster criheUum, sp. n. 



Rays 5. E. = 5r. 'R = A5 millira. in the 

 type specimen. 



Very closely related to P. subtuherculatus, Sladen, from the 

 South Pacific Ocean. 



No pedicellarise of any kind present. 



Disk of moderate size ; rays rather short. 



ALactinal surface covered with small paxill^e formed of 

 from six to twelve uniformly minute spiniform granules, three 

 or four round the madreporiform body, and one in each inter- 

 radius having about twenty granules. 



Marginal plates uniformly covered witli similar granules. 



Supero-marginal plates about 21, broad, tumid, almost 

 entirely abactinal in position, articulating rather obliquely 

 with one another ; each with a central eminence supporting 

 a single stout sharp spine. 



Infero-marginal plates broad, tumid, alternating with the 

 su})ero-marginals in the basal half of the ray, coinciding with 

 them in the distal half; each with a stout sharp spine at its 

 upper (abactinal) end. 



Adambulacral plates distant, broad, each with a furrow- 

 series of about twelve spinelets, standing in an almost circular 

 I'alisade round a single large actinal spine. Mouth-plates 

 liirge, each with a furrow-series of six or seven spinelets, of 

 ^^hich the most central (adoral) is many times larger than any 

 of the others and slightly larger even than the large actinal 

 spine of the plate, and with a suture-series of small spinelets. 



Actinal interradial areas small, not extending beyond the 

 third adambulacral plate, and carrying only about six finely 

 spinate plates. 



Anus central, distinct. Madreporiform plate small, situated 

 midway between the centre and the margin of the disk, and 

 outside a very big paxilla. 



