80 MANUAL OF THE MOLLUSCA. 



tho district, and 163 also occur in S. America. The fauna of 

 the Panama province is remarkably distinct from the other W. 

 American provinces, and especially the Caribbrean. At one 

 time it was thought that it did not possess a single sjoecies 

 identical with any occurring in the West Indies or the east side 

 of America. Dr. P. Carpenter, however, has shown that 35 

 marine shells (lo univalves and 20 bivalves) occur on both sidc3 

 of the Isthmus of Darien, and this number has been lately 

 increased. 



A few of the species even extend as far as W. Africa accord- 

 ing to Dr. Carpenter; he mentions 15, and among them the 

 following : — Crepidula iiurjuiformis, C. aculeata, Hipponyx anti- 

 quatiis, BanJcivia varians, Nutica maroccana, Marginella cceridcs- 

 cens, Nitiddla guttata^ Purpura p( in sa. Five species are common 

 to Mazatlan and the British coasts, viz., KelJia suborhicularis, 

 Lasea rubra, Saxicava arctica, Cijtiicrca Dione, TlydroJiia idvce. 

 Still more remarkable is the absence of resemblance between 

 the faunas of Panama and those of the Indo-Pacific area, there 

 being only seven forms common to the two. Thus, Cytherea 

 peticJn'alis occurs in Japan; Nasso. acuta, in Australia; and 

 OUva Dudosii, Natica maroccana, Nitidella criharia, Hipponyx 

 harhatus, II. Orayanus, are scattered over the Pacific ocean. 



The river- openings of this coast are bordered by mangroves, 

 amongst which are found Potamides, Areas, Cyrenas, Potamo- 

 myas, Auriculas, and Purpuras, whilst Littorince climb the trees 

 and are found uj^cn their leaves. The ordinary tide at Panama 

 amounts to 16 or 20 feet, the extreme to 28 feet, so that once a 

 fortnight a lower zone of beach may be examined and other 

 shells collected. The beach is of fine sand, with reefs of rocks 

 in the bay. 



Gallapagos Islands. — Out of 111 sea-shells collected hereby 

 Mr. Cuming, 43 are unknown elsewhere ; 25 occur in Mazatlan, 

 22 in Central America, 38 in Panama, but only 11 in South 

 America. 



Littoral shells common toPanama and the Gallapagos (C. B. Adams.) 



Cyprsea rubescens. Columbella nigricans. Turbinella cerata. 



Mitra tristis. Ricinula reeviana. Pleurotoma eccentrica. 



Planaxis planicostatiis. Cassis coarctata. Hipponyx radiata. 



Puii)ura carolinensis. Oniscia tuberculosa. Fissiirella macrotrema. 



Columbella atramentaria. Conus brunneus. „ riigro-pujictata. 



„ bicanalifera. „ nux. Siphonaria gigaa. 



„ hsemaswoma. Strorabua granulatns. 



