MAZATLAN UNIVALVES 199 



tenuissime longitudinalitcr granulato-striato, transversim minu- 

 tissime corrugato ; areis later alibus indistinctis ; superficie 

 tota valde gnanulatd, tuberculis splicer oidalibus et granulis 

 catenatim in lineis a jugo sub diver gentibus elegantissime in- 

 structd ; mucrone subconspicuo, subcentrali ; intus rosed seu 

 alba ; marginibus acutis et lobis valvarum non separatis, mag- 

 nis,fissura in utroque latere und, lobis angulatis, sinu maxima, 

 planato ; ad jugum tenuissime corrugatd, ad mucronem lamin- 

 aid ; valvd posticd hexagonali, duabus Jissuris ad terminum 

 divisd ; limbo pallii spiculis erectis translucidis copiose ornato ; 

 postice, antice, et ad suturas, spicularum quasi acicularum cristis 

 pulcherrime munito. 



Whether the varied colouring of this shell, its elegant sculp- 

 ture, the bird-like form of the medial or hexagonal shape of 

 the bifissured terminal valves, or the adornment of the mantle 

 with transparent needle-like hairs, rising now in tufts, now in 

 irregular crystals, be examined under the microscope, it would 

 be difficult to find any shell of such surpassing beauty. Only 

 one perfect specimen was found, but fresh valves belonging to 

 several other individuals were detected among the Spondylus 

 washings. The valves in the same shell greatly differ in colour, 

 as in L. albolineatus. The posterior valve is peculiarly exqui- 

 site in its form, colour and sculpture. There is considerable 

 variation in the size of the tubercles, and in the striation of 

 the jugum. The outer margin does not enclose the plates of 

 insertion, as it does in Lepidopleurus. Long. '16, lat. *06, alt. '02. 

 Hab. Mazatlan ; off Spondylus calcifer ; extremely rare ; 



L'pool Col. 



Tablet 907 contains the perfect specimen and 4 valves. 



FAMILY PATELLID^E. 

 GENUS PATELLA, Linn. 



As the shells in this genus can scarcely be distinguished 

 from those of Acmsea, the location of many of the following 

 species in this and the next family is doubtful. 



259. PATELLA MEXICANA, Brod. fy Sow. 



Zool. Journ. vol. iv, p. 369. Menke in Zeit.f. Mai. 1851, p. 37, 



no. 132. 



=Lottia gigantea, B. M. : Gould ms. 

 = Patella maxima, B. M. Cat. D'Orb. Moll. p. 53, no. 449. 



