158 GASTROCH^NID^. 



entirely obsolete. The inner margin is not crenated. 

 Were it not for this last character, the Pectunculus 

 truncatus of Da Costa, who, not delineating the species him- 

 self, refers for its representation to Borlase, whose figure 

 clearly is meant for Irus, might not unreasonably be 

 deemed an old worn example of this Venerupis. But as 

 Montagu justly observes, his species is involved in great 

 obscurity ; from which uncertainty, the language of its 

 author not strictly applicable to any British species, and 

 equally suited to more than one exotic bivalve, forbids all 

 hope of our being able to extricate it. 



Poli has remarked that it is very singular, whilst shells 

 of the Venerupis irus are cast up in profusion on the coasts 

 of Sicily, the animal is rarely found in them ; indeed, he 

 himself had never been able to meet with it. Common as 

 the shell is in the south, few observations have been made 

 upon its constructor. Deshayes has given an outline figure 

 of the animal in his " Mollusques d'Algerie." He repre- 

 sents the siphons as united for a considerable length, and 

 when separated of unequal lengths. One of them has the 

 fringe of cirrhi placed immediately around the margin ; the 

 other has a tube-like continuation beyond the fringe. 

 The cirrhi themselves are of two orders, the shorter one, 

 reflexed and simple, the longer projecting and pinnate. 



The valves rarely exceed half an inch in length and 

 three-quarters of an inch in breadth. They are found im- 

 bedded in limestone rocks at Plymouth and other parts of 

 Devonshire (Montagu) ; in large masses of rock opposite the 

 old castle at Weymouth (S. H.) Dead shells are frequent 

 in shell sand all along the Southern coast. In S. Wales it 

 has been found at Lan gland bay, near Swansea (Jeftreys). 

 In Ireland at Youghal (R. Ball); Howth (Turton) ; in 

 sponges and sea- weed at Miltown Malbay (W. Harvey). 



