71 



shell, which is sub-trigonal, flat and irregular, bears some 

 resemblance to P. Pusio, but the ribs are much larger and 

 more rugose. Corsica. 



78. P. aculeatus. (pi. xiii. f. 47.) Jefferys Conchological 

 Magazine. P. vitreus, Var. Chemn. t. 6/. f. 637. b. 



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

 elevatis, minute aculeatis ; auriculis insequalibus : postica 

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

 pallide 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 species 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 quite distinct. Great Britain. 



79. P. vitreus. (pi. xiv. f. 86-7.) Chemn. t. 67. f- 637- ((• 

 T. parva, compressa, sequivalvi, sub-tequilaterali, radiatim 



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

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



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

 Cuming from Sorsogon, resembles the figure given by 

 Chemnitz t. 67. f. G37, a. for the first variety of his P. vitreus. 

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

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

 aculeatus of Jeflerys. 



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

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



a;quilaterali ; auriculis ineequalibus, costatis, ad basin striatis, 

 postica parva, antica magna, costis kevibus, indistinctis, 

 planulatis, numerosis, interstitiis concentrice 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, very 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, Midler, domesticus, Chemn. 



T. ovali sub-trigona sub-ventricosa, fequivalvi, sub-aequi- 

 laterali, leevi vel obsolete striata, auriculis valde inajqualibus, 

 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, sequivalve, 



