HELCIONISCUS. 149 



tral callus is dark orange-brown, sometimes encircled by a whitish 

 ring. 



Length 40, breadth 32, alt. 15 mill. 



Suez (Fischer) ; Red Sea and GulfofAkaba (Smithsonian Cabi- 

 net) : Japan at HaJcodadi (Stimpson and Anthony in Phil. Acad. 

 Colin.) ; Australia. (Rve.) 



P. variegata REEVE, Conch. Icon, species 38 (Dec. 1854), not P. 

 variegata REEVE, Conch. Syst. pi. 136, fig. 1 (1842). P. variegata 

 FISCHER, Journ. de Conchyl. 1870, p. 167. Helcioniscus variegatus 

 DALL, Amer. Journ. Conch, vi. p. 277, t. 16, f. 27 (animal and den- 

 tition). Not Patella variegata DE BLAINVILLE, Diet, des Sci. Nat. 

 xxxviii, p. 100 (1825). 



Readily distinguished from P. rota by its blotched and speckled 

 color-pattern. 



Part of the localities given above are no doubt incorrect. I have 

 examined a very large series, and find but little variation from the 

 typical form. I have seen no specimens approaching P. rota. 



Reeve in 1842 described and figured a specimen of typical P. rota 

 Gm. under the name variegata. In 1854 he shifted that name to 

 the present species, giving no reason for such change, nor even 

 admitting that he had made a change. Under these circumstances 

 it becomes necessary to give a new name to the present species, and 

 thus avoid the confusion otherwise inevitable. It should also be 

 noted that there is a prior P. variegata of Blainville, 1825. 



H. CERNICA (Barclay) Adams. PI. 71, figs. 59, 60. 



Shell thin, ovate, depressed-conic; decussated with numerous 

 obtuse radiating ribs and close, elevated, undulating concentric 

 lirse; whitish, ornamented with reddish-brown rays. Apex sub- 

 central, obtuse ; aperture ovate. 



Interior sculptured and colored like the outside, shining, somewhat 

 pearly ; margin more or less widely crenulated. 



Length 39, breadth 29, alt. 10 mill. (Ad.) 



Barkly Island, Mauritius. 



Nacella (Celland) cernica Barcl. ms., H. ADAMS, P. Z. S. 1869, p. 

 273, t. 19, f. 7, 7a. 



This species is the type of H. Adams' subgenus CELLANA. It 

 probably belongs to Helcioniscus rather than to Nacella or Patinella. 



