1890.] MARINE MOLLUSCA OK ST. HELENA. 299 



be iucliiied to place tliis form in the Aclceonidce, as recomnfi ended by 

 Adams, rather than in tiie Pt/rainirlellida-. 



Some confusion appears to exist with regard to tlie geuus Mono- 

 ;^^y^»«a, judging from the variety of shells which have been placed 

 in it. The original type described by Lea under the name of M. 

 aJabamensis is a fossil, and evidently allied to Ancillaria, with which 

 it is associated both by Tryon and Fischer in their recent Manuals. 

 A. Adams published a monograph of this genus in the ' Proceedings 

 of the Zoological Society ' for 18.51 (reproduced in Sowerby's ' The- 

 saurus Conchyliorum,' vol. ii.), including in it a number of species, 

 none of which, in fact, have any relationship with Monoptygma. 

 He subsequently removed all of these species to other genera, with 

 the exception of M. striatum and M. fulvum. A species very 

 closely allied to these forms has since been described by Lischke 

 from Japan, under the name of M. eximium. As far as I can 

 ascertain, no generic or subgeneric division has l)een proposed for 

 these species. If as much latitude in variation of form be allowed 

 in the genus Leucotinu as in some other genera (e. g., Murex, 

 Triton, Mitra, &c.), there is no occasion to establish a new division 

 tor these three and allied species, for, with the exception of being 

 more elongate than typical species of the genus, they do not offer 

 any material differences in regard to the aperture, sculpture, or the 

 apical whorls. 



Umbrella mediterranea, Lamarck? 



This well-known JMediterranean shell also occurs at Madeira and 

 the Cape de Verde Islands, but it has not previously been recorded 

 from so southern a locality as St. Helena. Krauss' quotes U. indica 

 as a Cape species, so that 1 am uncertain whether the two young 

 shells from St. Helena should not be leferred to that species, if in 

 reality it is distinct from the Mediterranean form. It is stated by 

 Eydoux and Souleyet, in the 'Zoology of the Eonite,' that the 

 animals do not differ, and, as far as I have studied the shells, the 

 two typical forms appear to pass one into tlie other. 



Tylodina citrina, Joannis. 



Tylodina citrina, Joannis, Mag. de Zool. 1834, pi. oti ; Grube, 

 Ausflug Triest uud Quarnero, pp. 58 & 120. 



Hab. Mediterranean {Joannis, Qrube, Monteromto, ^c.) ; Canary 

 Islands {IfcAndrew, teste Weinkauff). 



Only some small specimens, about 7 millim. in length, were ob- 

 tained. They agree in every particular with the apical portion of 

 large Mediterranean examples with which I have compared them. 

 The minute nucleus consists of about two spirally-coiled whorls, is 

 glossy, vitreous, and laterally incliued. 



1 Siidafr. Moll. p. (32. 



