shell, which is sub-trigonal, flat and irregular, l)ears some 

 resemblance to P. Pusio, ]>ut the ribs are much larger and 

 more rugose. Corsica. 



78. P. ACULEATus. (pi. xiii. f. 47.) J^^erys Conchological 

 Magazine. P. vitreus, Var. Chemn. t. 67. f. 6.37. 6- 



T. oequivalvi, sub-ovali, tenui, radiatim striata, striis punctis 

 elevatis, minute aculeatis ; auriculis inccqualibus : postica 

 parva, antica magna, alterius valvfc, valide emarginata ; colore 

 palUde luteo, rubro-nebulato. Long. 0. 80. ; lat. 0. 20. ; alt. 

 0. 90. ; poll. 



The specimen from which our figure is taken was found in 

 breaking up a mass of a British sjjecies of Serpula. It is 

 identical with the shell figured by Chemnitz in association 

 with, and as a variety of, his P. vitreus, which however, 

 according to his own statement, is qviite distinct. Great Britain. 



79. P. VITREUS. (ph xiv. f. 86-7.) Chemn. t. 67. f. 637. a. 

 T. parva, compressa, fequivalvi, sub-cequilaterali, radiatim 



striata, alba, griseo-punctata ; auriculis latis, sub-a3qualibus. 

 Long. 0. 40. ; lat. 0. 10. ; alt. 0. 50. ; poll. 



The small shell here figured, which was brought by Mr. 

 Cuming from Sorsogon, reseml^les the figure given by 

 Chemnitz t. 67- f. 637, a. for the first variety of his P. vitreus. 

 which, from the description, as well as from the figure, differs 

 entirely from the shell figtired as a second variety, the P. 

 aculeatus of JeflTerys. 



80. P. CORNEUS. (pi. xiii. f. 44-5. pi. xx. f. 244-5.) nobis. 

 T. pellucida, tenui, eequivalvi, rotundato-ovali, oblique sub- 



scquilaterali ; auriculis ineequalibus, costatis, ad basin striatis, 

 postica parva, antica magna, costis Isevibus, indistinctis, 

 planulatis, numerosis, interstitiis concentri(te minutissime 

 striatis. Long. 0. 47.; lat. 0. 25.; alt. 0. 52.; poll. 



A light transparent species, of a horny colour and texture : 

 the anterior auricles are much larger than the posterior, the 

 ribs are irregular, veiy slightly raised, flattened and smooth : 

 the interstices are very finely striated across. When young, 

 the shell is radiated by several bands of brown. Magellan. 



81. P. OBSOLETUS. (pi. xiv. f. 74, 75, 79.) Pennant. Brit. 

 Zool. t. 61. f. 66. Tigerinus, Miiller. domesticus, Chemn. 



T. ovali sub-trigona su1)-ventricosa, fequivalvi, sub-fcqui- 

 laterali, kevi vel obsolete striata, auriculis valde in£eqvialibus, 

 posticis minimis, anticis magnis, sulcatis ; colore, valde 

 vario, plerumque maculis purpureis, albis, luteisque variegato. 

 Long. 0. 84. ; lat. 0. 30. alt. 0. 90. ; poll. 



Oval, inclining to triangular, nearly equilateral, cequivalve, 



