240 lucinid^:. 



and not less to the continual and successful labours of 

 Deshayes, Dunker, Pfeiffer, Hanley, Reeve, H. & A. 

 Adams , Morch, Fischer, and other writers on the subject. 

 New forms are every day being brought to light, and re- 

 quire the former system of classification to be modified. 

 The old tree has put forth a greater number of new 

 shoots than the branches which have been severed from 

 it, and it is not less vigorous for the pruning ; even the 

 loppings, that have been planted and carefully tended, 

 are flourishing, and bid fair to rival their parent stem. 

 Species of Lucina abound in tropical seas, and Dr. Philip 

 Carpenter has enumerated no less than seventeen as 

 inhabiting the west coast of North America. Lamarck 

 asserted that in certain species the teeth become obli- 

 terated by age and disappear, which statement has been 

 repeated by subsequent waiters. The British species 

 present no such anomaly ; on the contrary, their teeth 

 are developed in the course of growth, and become 

 stronger and more conspicuous in the adult than in the 

 young. 



1. Lucina spini'fera*, Montagu. 



Venus spinifera, Mont. Test. Brit. p. 577, pi. 17. f. 1 . L. spinifera, F. & H. 

 ii. p. 49, pi. xxxv. f. 1. 



Body clear white : foot very slender, and not swollen. 



Shell obtusely triangular, with a somewhat oblique out- 

 line, compressed, solid and opaque, not glossy. Sculpture, 

 about 30 fine, plate-like concentric ridges, which are slightly 

 imbricated, their edges forming sharp spines on the dorsal 

 margin ; these ridges are more regular and equidistant in the 

 young than at a later stage of growth ; between them are 

 extremely numerous and fine, but irregular concentric striae ; 

 and there are here and there a few longitudinal lines which 

 are not visible to the naked eye : colour pale yellowish-white : 

 epidermis fibrous and not very thin : margins slightly incurved 



* Prickly. 



