76 



colore fusco-rubescente, vel purpureo, vel aurantiaco. Long* 

 3. 10. ; lat. 1. 10. ; alt. 3. 20. ; poll. 



Rounded, oval, oblique, ventricose, thin, equivalve ; with 

 unequal sulcated auricles ; ribs 25, angular, serrated at the 

 sides and having small, regular, erect, scales. The colour of 

 the most common variety is reddish brown ; while some 

 specimens are orange red and others purple. Found in sponge. 



New Holland. 



95. P. Australis. (pi. xix. f. 210, 220.) nob. 



T. sub-ovali, ventricosa, crassiuscula, ajquivalvi, inaequi- 

 laterali, postice sub-expansa : auriculis imequalibus, scabroso- 

 sulcatis ; costis 23 crassis, sub-angulatis, trifariam divisis, 

 lateribus serratis, angulis squamatis; interstitiis planis. Long. 

 1. 45. ; lat. 0. 55. ; alt. 1. 50. ; poll. 



The shell is thicker and rounder than P. asperrimus, with 

 fewer and less angular ribs and flat interstices. The ribs are 

 composed of two rows of small, sharp points and a central 

 ridge with scales. Swan River. 



96. P. varius. (pi. xix. f. 214. 218.) Linn. Syst. Nat. p. 

 1146. Ostr. muricata, punctata, mustellina, violacea, tenuis, 

 versicolor (f. 216), incarnata, media, ochreoleuca, flammea, 

 Gmel. 



T. sub-ovali, tenui, sub-irregulari, valva sinistra paululum 

 majori, umbonibus angustis ventricosis : auriculis valde 

 iiia^qualibus; muricato-sulcatis: postieis parvis, obtusis; anticis 

 ir.agnis, acutis ; dextrae valvee antica longitudine alteram 

 superante, margiue valde inflexa et squamata, ad basin valde 

 emarginata ; costis 27 ad 30, sub-quadratis distantibu?, 

 squamas erectas, acutas, distanter ferentibus : interstitiis 

 latiorihus, colore vario. Long. 2.; lat. 0. 75. ; alt. 2. 25.; 

 poll. 



Rather oval, lengthened, thin, not quite regular, with the 

 under valve rather smaller than the upper, which is slightly 

 ventricose near the umbones : the anterior auricles are much 

 elongated, that of the upper valve considerably overlapping 

 the other at the margin, with the sinus very large : ribs from 

 20 to 30, muricated by distant, erect, sharp scales, the 

 interstices smooth, rather wider than the ribs. Some varieties 

 are considerably smoother than others, with a greater number 

 of ribs. The variations in colour are numerous. In the 

 variegated varieties the white patches have an angulated 

 character. Great Britain and Mediterranean, 



97. P. SFLEXDiDULUS (pi. xx. f. 246.) nob. 



T. ovali, sub-trigona, tenui, compressa, ad latera angulata ; 



