182 REV. R. T. Lowe's list of shells 



Somewhat resembling a lAmncea palustris (MiilL), or a L. 



peregra, Drap. Shell thin ovate, with a nearly perfect pointed 



apex, of a plain olive-brown, pale at the suture, or uniform black. 



Five examples only. Spring or river at the Emperor's Garden. 



b. Forma turrita ; testa crassiore solidiuscula, anfr. ultimo spiram sub- 



aequante. 

 Long. 7-16 lin.,anfr. l"'4-8; lat. 3-7. 



Melanopsis Dufourei, " Fer.," Lam. ed. 2. viii. 493; Graells, Catal. 17. 

 flf. 20-22 ; Rossm. xiv. 28. t. 68. if. 836-840*. Bucoinum Maroccanum, 

 Chemn. xi. 285. t. 210. fF. 2078, 2079 (test* majores decorticatse, 

 ideoque, ut rarius inveniuatm', fasciatse). 



Found with /3 1 in the spring or river, but comparatively rare. 



Nothing can be more variable than the individuals of the present 

 species, as thus constituted, in size, colour, shape, and sculpture ; 

 and only the possession of large suites of examples could warrant 

 the fusion into one of forms which, if judged only by detached or 

 isolated instances, might well be considered as so many distinct 

 species. In size it varies from 3 or 4 to 12 or 15 lines long ; in 

 colour, from deep uniform brown or black (the prevalent hue in 

 small examples) to pale straw or bluish-white, irregularly streaked 

 longitudinally vdth brown or fulvous lines ; the shape passes by 

 degrees from shortly ovate to turreted-elongate, from broad to 

 narrow-oblong, and from a blunt or decollated to an acuminate 

 finely pointed apex. The ribs vary in number from 12 to 20, 

 sometimes covering the whole shell, sometimes confined to the two 

 or three apical volutions, and passing gradually through every inter- 

 mediate stage of prevalence or strength into absolute evanescence. 

 And all these characters are so variously blended and combined, 

 that not any one of them can be selected as more regularly typical 

 or predominant, or less liable to change and alteration, than 

 another ; i. e., you have ribbed and even both small and large, 

 black and pale, short and elongate, blunt and pointed, strong and 

 thin ; or, again, ovate and elongate both small and large, black and 

 pale, ribbed and even, thick and thin, blunt and finely pointed, 

 &c. &e., in every variety of combination. It is merely, therefore, to 

 simplify the synonymy, by an arrangement in accordance with the 

 two pseudo-species of Lamarck and Ferussac, that the seulptiu-e is 

 here taken as of primary importance in the grouping of these forms. 



* His f. 835, considered (p. 30) as the typical form of M. Dufourei, Per., 

 belongs i-ather to the var. Graellsii, p. 31, ff. 841-843 and 844 ? (M. Graellsii, 

 Villa, Gi'aeUs, Catal. 17. if. 16-19), characterized by the tzvo depressed belts of 

 the last volntion. This form or var. did not occm" at Mogador. 



