PATELLA. 93 



ing; apex acute, curved over, somewhat hooked, situated nearly at I 

 of the length. Margin acute, obsoletely plicate and crenulated be- 

 neath. Interior somewhat hoary and bluish, the center dull white 

 and yellowish. Length 31, breadth 22, alt. 8 mill. (Dkr.*) 



Loanda, West Africa. 



P. kraussii DKR., Ind. Moll. Guin. Infer., p. 42, t. 6, f. 4-6, 1853. 



There are 100-120 radiating libs; the intervals between the 

 larger ribs are occupied by' 2 or 3 smaller riblets. The larger ribs 

 are scaly and nodulous ; and the whole surface is very delicately 

 lineated. 



P. COMPRESSA Linne. PI. 61, figs. 68, 69, 70. 



Shell thin, narrow, oblong, the sides compressed and parallel ; con- 

 ical, the apex in front of the middle and curving forward. Covered 

 with close unequal radiating riblets ; dull straw-colored, the young 

 often finely dotted, spotted or rayed with bright crimson, pink or 

 orange often marked with opaque-white dots or triangles. 



Interior white, or in the young marked like the outside. Edge of 

 the shell even, the ends elevated. 



Length 94, breadth 45, alt. 35 mill. 



Cape Good Hope. 



P. compressa LINN., Syst. x, p. 783. KRAUSS, Su'daf. Moll. p. 

 50. Q. & G. Yoy. de 1'Astrol., iii. p. 338, t. 70, f. 1. REEVE, 

 Conch. Icon.f. 13a, and of authors. P.miniata BORN, Test. Mus.Cses 

 Vindob. p. 420. LAM., An. s. Vert, vi, p. 333. KRAUSS, DieSiidaf. 

 Moll. p. 51. P. umbella GMEL., Syst. p. 3706. LAMARCK, An. s. 

 Vert, vi, p. 327. REEVE, Conch. Icon. f. 17. P. sanguinolenta 

 GMEL., Syst., xiii, p. 3716, no. 130. P. sanguinalis RVE., Conch. 

 Icon. f. 95. 



This species is readily known by its compressed sides, elevated 

 end-margins, and straw-yellow color. It is occasionally found varie- 

 gated with red on the upper part of the cone, and the young are 

 almost always so marked. 



Dead specimens have been found at St. Helena, doubtless drifted 

 thither on seaweed. (See Smith, P. Z. S., 1890, p. 248.) 



The typical form of this species is never found living on shore. 

 It lives upon large seaweeds, as one might readily tell by the form 

 of the shell. When living on rocks it develops into the form known 

 as P. miniata. Specimens which have changed their stations and 

 show a corresponding abrupt change of sculpture are not very 



