OPHIUROIDEA 219 



Lives on sandy bottom, buried about a decimetre deep in the 

 sand, with the point of the arms just protruding above the ground 

 surface. Development unknown. Commensal with this brittle 

 star are found the mussel Montacuta hidentata and the Polynoid 

 Harmotkoe lunulata, in its young stages ; larger specimens of this 

 worm are found living on Synapta or on other Polychsete worms. 



In British seas this species has been found at the south coast 

 (especially common in the Salcombe Estuary, where it may be 

 dug out at very low tide), Clare Island, coast of Down and 

 Antrim, Kerunare River, Tenby, Firth of Forth, and the Clyde. 

 May well be supposed to occur all round the coasts in suitable 

 localities. It is elsewhere known only from the west coast of 

 Sweden, the Danish North Sea coasts, and further along the 

 French coasts. (The Mediterranean form is maintained by 

 Gislen as a separate species, A. neapolitana (M. Sars).) It is not 

 known from greater depths than 40 m. 



3. Paramphiura Koehler. 



Differs from Amphiura in the outer mouth papilla being 

 developed into a large rounded scale, which covers most of the 

 jaw, almost joining its neighbour in the mid-line, and assuming 

 the aspect of an extra plate so that there are apparently two 

 pairs of plates between the infradental papillae and the adoral 

 plates. 



Only one species known.^ 



1. Paramphiura punctata (Fovhes). (Fig. 124.) 

 (Syn. Ophiocoma punctata Forbes.) 



Both sides of disk covered with fine scales. Primary plates 

 not distinguishable. Radial shields very narrow, linear, parallel, 

 wholly separate. Dorsal arm plates elongate, rounded ; ventral 

 plates elongate, nearly rectangular, with somewhat excavated 

 outer edge ; 5 slender arm spines ; 2 small tentacle scales. 



^ Koehler, to whom we are indebted for the description and 'figures of 

 this form (the original description by Forbes being quite unsatisfactory), 

 regards Amphiura tritonis Hoyle as belonging to the present genus, and is 

 followed herein by H. L. Clark. The present author cannot agree with 

 this view, but must regard the form described by Hoyle as a typical 

 Amphiura (cf. p. 213). The interpretation of the extra plates on the jaw 

 as representing the outer mouth papillae would seem to be correct. But 

 it would be very desirable to have this interesting form made the object 

 of a renewed study. 



