ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 237 



five probably, members of the fauna : of the remaining ten, it is unsafe to 

 hazard a conjecture. 



The above analysis has been attempted, partly in order to show the diffi- 

 culties attendant upon all inquiries of this kind. Here is a collection made 

 on a single spot by a competent gentleman*, and described by a concholo- 

 gist of acknowledged superiority, the editor of one of the very few strictly 

 Conchological Journals ; and yet only 32 can be accepted in the state in 

 which they are presented, the remaining 27 containing errors either of col- 

 lection or of description. If such is the work of a master, the readers of 

 this Report will accept with due caution the labours of a mere student. 



49. But if there is so much doubt attaching to Menke's first list, there is 

 still more in the principal list which follows. In the Zeit.f. Mai. 1850, no. 11, 

 Dr. Menke informs us that since his last paper, M. Melchers had again 

 visited Mazatlan, and had investigated the shells of that region with great 

 zeal and perseverance, and no little sacrifice of money. He returned to 

 Bremen in the summer of 184-9, and generously presented Dr. Menke with 

 a selection in the autumn of 1850. So far all is extremely satisfactory; but 

 he goes on to state that he received at the same time, from the same ship, 

 a box obtained at Mazatlan by purchase. This fact invalidates the soundness 

 of all that follows ; except in those few instances in which we are informed 

 that M. Melchers collected the shells himself. The following list there- 

 fore must be received with great caution, except where the shells are con- 

 firmed by other authority. Occasionally Dr. Menke gives particulars as to 

 the number of individuals from which he describes; as when he tells us, 

 p. 188, that, as he has had an opportunity of examining no fewer than eight 

 specimens of Murex ambiguus, Rve., he can speak with authority as to its 

 being distinct from M. nigritus, Phil. If he had examined the many 

 hundreds in the Reigen collection, he would probably have come to a different 

 conclusion. The second (mixed) list is as follows : — 



1850, pp. 161-173. 



1. Bulla Adamsi, Mke. 

 2. nebulosa, Gld. 



3. (Tornatina) gracilis, [Mke. 



quasi] A. Ad. = IB. infrequens, 

 C. B. Ad. 



4. Bulimus zebra, Desh. 



5. Planorbis tenagophilus, [Mke. q.] 



D'Orb. =P. tumens, Cpr. 



6. Physa Peruviana, [Mke. q.] Gray, 



=Ph. aurantia, Cpr. 



7. Lit orina fas data, Gray. 



8. aspera, Phil. 



9. • ■ modesta, [Mke. q.] Phil. ?= 



L. conspersa, Phil. var. 



10. Turritella tigrina, Kien. "=No. 3 



of first list." 



11. goniostoma,Yn\. 



12. Hookeri, [Mke. q.] Rve. 



13. Vermetus Panamensis, Rouss. The 



figure quoted represents Le Ver- 

 mel of Adanson. The name 



has not been found. 1—Bivonia 

 contorta, var. 



14. Vermetus glomeratus, [Mke.q.]Rous. 



?=Bivonia contorta, Cpr. 



15. Natica Recluziana, Desh. 



16. glauca, [?] Humb.= N. patula, 



Sow. 



17. maroccana, (Chemn.) Koch. 



18. ovum, Mke. 



19. Neritina cassiculum, Sow. 



20. picta, Sow, 



21. Nerita ornata, Sow. " =N. multi- 



jugis, Mke." =N. scabriuscula, 

 Lam. 



22. funiculata, Mke. = IV. Bern- 



hardi, Reel. 



23. Planaxis acutus, Mke. =P. nigri- 



tella, Forbes. 



24. obsoletus, Mke. =P. nigri- 



tella, var. 



25. Turbo Jluctuosus, Wood. 



26. Solarium granulatum,[Mke.q.']ljSLxn. 



* As M. Melchers is quoted for a shell from Vera Cruz, on the Gulf of Mexico, Zeit. f. Mai. 

 148, p. 3, it speaks much for his accuracy as a collector that no W. Indian species are 



quoted in Menke's lists, except such 

 have probably been mistaken. 



have analogues on the Pacific coast, for which they 



