104 GEOLOGICAL MEMOIRS. 



limited, and that of the fresh-water tribes is almost entirely absent, 

 we ought not to wonder, although it appears scarcely credible, 

 that the list of the marine inhabitants is so small as we find it 

 recorded. 



There are, comparatively, but few genera adorning the shores of 

 the Canary Islands which are absent in South Italy : among them, 

 however, are Voluta, Terebra, and Crassatella, and the tropical 

 genus Conus is already represented by four species out of seventy- 

 three (the whole number of marine Gasteropoda), although other 

 tropical genera Nerita (in its limited sense), Strombus, Pterocera, 

 Tridacna, &c, are not yet met with. 



It may be remarked, that many of the commonest South Italian 

 species are absent in the Canaries ; as, for instance, all the Solens, 

 all the Tellince, Cythercea Chione and exoleta (the latter re-ap- 

 pearing in Senegal) ; Venus decussata, geographica, gallina ; Car- 

 dium echi?iatum, aculeatum, erinace?im, papillosum ; almost all the 

 Pectens, all the Anomias (not a single species described); every 

 species of Fissurella, Calyptrcea, Crepidula, and Rissoa (one 

 species of Rissoa is described) ; all the Natieas and Vermetus (not 

 one of this latter being known) ; Trochus granulatus, Conulus, 

 crenidatus, striatus, divaricatus,fanulum, umbilicaris ; Phasianella 

 speciosa ; Turbo neritoides (L. non auct.); Pleurotoma ; Fusus 

 (not one species of either mentioned) ; Murex erinaceus, cristatus, 

 Edivardsii ; Tritonium corrugatum ; Chenopas pes pelicani ; 

 Cassidaria ; Buvcinum variabiles d 'Orbignyi, corniculum, neri- 

 teum, pusio L., scriptum L. ; Cyprcca coccinella ; Conus mediter- 

 raneus; Helix naticoides, aspersa, vermiculata, strigata, variabilis ; 

 Clausilia (not one species appearing to inhabit the islands). 



4. Comparison of the Fauna of Senegal ivith that of South Italy. 



Adanson has given a list of the mollusca of Senegal in his ad- 

 mirable and well-known work, but this list is very incomplete and 

 enumerates only 196 species, the same number, it will be observed, 

 as that obtained from the Canary Islands. This incompleteness 

 is the more to be lamented, because a number of the species enu- 

 merated by him are new and still without systematic names, not- 

 withstanding that his countrymen have remained for a century in 

 undisturbed possession of the district traversed by him. It ap- 

 peared to me of great consequence, however, to determine which 

 of the Mediterranean species extended to Senegal, and I have 

 therefore myself endeavoured to make out this so far as the figures 

 and descriptions would enable me to do it. The following tables 

 are the result of this endeavour to attain my object : — 



Marine Bivalves. 



Teredo navalis L., Taret. Cytberea exoleta I.., Cutan. 



Solen legumen L.,Molau. Venus verrucosa L., Clonisse. 

 Solecurtus strigilatus L., Golar. decussata L., Liinot. 



Donax truneulus L., Gafct. Pectunculus pilcsus L. ? Vovan. 



Lutraria piperita Gm , CalcineUe. Spondylus Gajderopus L., Guron. 



