182 ECHIN0DERM8 OF THE BRITISH ISLES 



Colour mainly as the preceding species, but the disk often with 

 small whitish rings surrounding a darker spot ; arms banded with 

 brownish and whitish. The colour (of both species) keeps fairly 

 well in alcohol. This species upon the whole is somewhat coarser 

 and appears to grow somewhat larger than 0. aranea. 



Biology i)robably as in the preceding species. Development 

 unknown. 



In British seas this species has hitherto been found only on 

 the Irish west coast (Birterbury Bay, Kenmore Bay ; A. M. 

 Norman).^ It is elsewhere known only from the Mediterranean 

 and from the Moroccan coast. Bathymetrical distribution ca. 

 GO- 100 m. 



IV. Family Ophiacanthid^ 



Disk more or less closely covered by spines, stumps, or 

 granules, which in a varying degree conceal the scales ; more 

 rarely {Ophiolebes) a thick, almost naked skin conceals the scales of 

 the disk and even the arm plates. A continuous series of mostly 

 pointed, papilliform, more rarely spine-like mouth papillae ; a 

 single, unpaired infradental papilla. A single series of pointed 

 teeth, no tooth papillae. Second pair of tube-feet inside the mouth 

 edge. Spines erect, often very long. Arms often distinctly 

 knotted, the proximal part of the segments being restricted, the 

 distal part with the lateral plates swollen. 



This family includes very numerous forms, and is one of the 

 largest of the families of Ophiuroids. Most of them are deep-sea 

 forms ; some of them {e.g. Ophiomyces, known from the North 

 Atlantic) being among the most remarkable of Ophiuroids. They 

 very often cling to corals, sponges, and the like, their arms being 

 to some degree able to roll in ventrally ; this they often do also 

 on preservation, which may make examination more difficult. 

 They are probably detritus feeders, and are, on the whole, 



^ The author is incUned to think that A. M. Norman perhaps made a 

 mistake in identifying the specimens from the loeaHties on the Irish 

 coast as 0. annulosa. In his note, " Ophiopsila annulosa (M. Sars), a 

 British Ophiurid " {Ann. Mag. Nat. Hist. (7) xiv. pp. 360-61, 1905), he 

 states that he got this same species from Plymouth, where it had been found 

 to be not imcommon in crevices of the red sandstone, especially in old 

 Pholadidea crypts in 15-25 fms. on the Mewstone Ledge and Stoke Point 

 Grounds. But this is exactly the locality of Ophiopsila aranea, which here 

 grows to a very considerable size, just like 0. annulosa. At the same time, 

 liowever, Norman says that he regards 0. aranea as a distinct species, 

 characterised by its fewer arm spines. The matter is doubtful, and, until 

 new records of the occurrence of 0. annulosa in British seas are at hand, 

 its presence there can scarcely be regarded as definitely settled. 



