80 MANUAL OF THE MOLLIJSCA. 



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

 the Panama province is remarkably distinct from the other W. 

 American provinces, and especially the Caribbsean. At one 

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

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

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

 marine shells (15 univalves and 20 bivalves) occur on both sides 

 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 T)t. Carpenter; he mentions 15, and among them the 

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

 quatus, JBankivia varians, Natica maroccana, Marginella coerides- 

 cens, Nitidella guttata, Purpurapansa. Five species are common 

 to Mazatlan and the British coasts, viz., Kellia siihorhicularis, 

 Lasea rubra, Saxicava arctica, Cytlierea Dione, Hydrohia 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, Cytlierea 

 petkhialis occurs in Japan; Nassa acuta, in Australia; and 

 Oliva Budosii, Natica maroccana, Nitidella criharia, Hipponyx 

 harbatus, H. Grayanus, 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 X^Y^ormce climb the trees 

 and are found upon 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. 



QaUapagos 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 to Panama and the Gallapagos (C. B. Adams.] 



CyipTiea rubescens. Columbella nigricans. Turbinella cerata. 



Mitra tristis. Ricinula reeviana. Pleurotoma eccentrica. 



Planaxis planicostatus. Cassis coarctata. Hipponj'x radiata. 



Pui-pura carolinensis. Oniscia tuberculosa. Fissui-ella macrotrema, 



Culunibella atramentaria. Conus brunneus. „ nigro-punctata. 



„ bicanalifera. „ mix. Siphonaiia gigas. 



„ liEeiuastoma. Strombus granulatus. 



