ECHINODEHMATA. 139 



10. OpMocoma brevipes. 

 Peters, Archwfur Natur. 1852, p. 85 ; see lyman, p. 27. 



Mr. Lyman (Frel. List, p. 27) gives as synonyms of this, his own 

 0. insvlaria (about which there will, I suppose, be no dispute), the 

 0. ternispina of Martens, an unnamed specimen of which, from 

 the island of Mauritius, has been for many years in the collection of 

 the British Museum and has for a long time been a source of much 

 disquiet to myself (I am now persuaded that this is a specimen to 

 which Dr. von Martens would have given the name ternispina), 

 OpMocoma variegata and 0. Irevispinosa of E. A. Smith, from the 

 island of Rodriguez. I do not know that a more western locality 

 than the island just named has ever been recorded by a zoologist ; 

 at any rate, Dr. Haacke did not detect the species among the Ophi- 

 urids collected by Prof. Mdbius in the island of Mauritius *, unless 

 he has been, as is possible, misled by the definition of 0. squamata 

 given by Miiller and Troschel ; the three or four lateral spines, the 

 two tentacle-scales, and the square markings on the upper arm- 

 plates might deceive a hasty nomenclator, but they could not, I 

 think, mislead any one who refers to the second edition of Lamarck 

 (vol. iii. 1840), p. 225, where he will find references to the plates 

 of Link and 0. F. Miiller. Although the species there figured ir> 

 regarded by the editors as distinct from 0. squamata, the resemblance 

 between such an O^hiurid as this OpMocoma and the OpMothrix 

 pentaphyllwm. GguTed by the two just-mentioned naturalists, is so 

 very slight that we are forbidden from supposing that the OpMura 

 squamata, Lamk. {OpMocoma squamata, M. & Tr.), is a near ally of 

 an Ophiothrix or OpMothrix-\ils.e form. 



The variations exhibited by this very widely distributed species 

 are indeed remarkable. It seemed for a time that the larger number 

 and smaller size of the mouth-papillae at the inner angles of 0. varie- 

 gata and of 0. Irevispinosa would indicate a certain difference ; but 

 a difference of quite equal extent can be detected in the mouth- 

 organs of a single specimen. The hollow square marking on the 

 upper arm-plates, which, when well developed,! seems to give such a 

 characteristic appearance to the arms of this species, may be replaced 

 by a black patch, or there may be a transverse bar, or there may be 

 only the two lines left which run parallel to the long axis of the 

 arm ; again, there may be spots, or the coloration may be fairly 

 uniform. The colour of the disk may be pale, spotted, or reticu- 

 lated ; the mouth-shields spotted or uniform in colour. 



Levuka, Fiji. 



* Mobius, ' Beitrage zur Meeresfauna der Insel Mauritius ' &o. (Berlin, 1 880). 

 In what follows I may seem to speak somewliat harshly of Dr. Haacke's services ; 

 but I am bound to point out that the list of Ophiurids given on p. 50 of this 

 work has no scientific value whatever. 0. dentata has been for many years 

 regarded, first by Lyman (1865) and since by others, as " only a middling-sized 

 0. eehinata;" the type of 0. squamata has been lost, " and nobody can tell 

 what it was, though it might have been 0. hrefoipes." Dr. Haacke makes no 

 reference' to either of these judgments. 



