1910.] AND INVERTEBRATES OF ST. HELENA. 125 



of the exact locality where I obtained it, but think it was caught 

 in the trammel in 4 fathoms, off Banks' Yalley, to the east of 

 Jamestown. It is common in the West Indies. 



ECHINOMETRA SUBANGULARIS. 



Cidaris subangularis Leske, 1778. 



Echinometra subangularis Desmoulins, Actes Soc. Linn. 

 Bordeaux, 1837. 



Echinometra acufera Blainville, 1834 ; Melliss. 



This is the species which is mentioned by Melliss under the 

 name E. acufera Blainville. He refers to its abundance and to 

 the fact that it lives in holes bored by itself in the solid basaltic 

 rock. The rocks along the shores are everywhere studded with the 

 holes inhabited by this urchin, which is of a black colour like the 

 rock itself, and the animal is so firmly attached in its hole that it 

 is difficult to dislodge it. A large number of sea-urchins are 

 known to have this power and habit of excavating cavities in 

 hard rock in which they dwell. In the Natural History Museum 

 is a fine photograph of limestone rocks full of such holes inhabited 

 by Strong ylocentrotus lividus, at Bundoran, South Donegal, in 

 Ireland. It is held that the boring is effected by the action of 

 the animal's teeth and spines, and it seems that the animal never 

 quits its hole even to feed. Apparently the sea-urchin obtains 

 enough nourishment from the organic substances which are washed 

 into its cavity. Simroth gives a good account of the habits of 

 the boring form Toxopneustes lividus, apparently a synonym of 

 Strongylocentrotus lividus, in the Azores. Mobius states that at 

 Mauritius the holes of two boring species are narrower at the 

 apertures than in the interior, so that it is impossible for the 

 animal to quit the cavity. At St. Helena, and in some other 

 cases, the cavities are only a little deeper than the diameter of the 

 animal ; but at Croisic and Douarnenez, on the coast of France, 

 according to Caillaud, the holes are 30 to 50 cm. deep. The 

 object of the habit is evidently to protect the animal against the 

 force of the breakers by which, if exposed, it would run the risk of 

 being killed, and on the coasts of oceanic islands like St. Helena 

 the necessity for such protection is very obvious. (For a summary 

 of the subject and its literature see Bronn's ' Thierreich,' Bd. ii. 

 Abth. 3, p. 1296.) 



E. subangularis occurs apparently everywhere in the tropical 

 Atlantic, at the West Indies and Gulf of Mexico, the Bermudas, 

 the whole coast of Brazil, the west coast of Africa, Cape cle Verde 

 Islands, and Ascension. 



Class ASTEEOIDEA. 



LlNCKIA. 



Two specimens belonging to this genus were taken in the trawl 

 at 20 fms. west of Jamestown, but according to Mr. Jeffrey Bell 

 they are too young for specific determination. 



