134 Cliusan Shells. [No. 2. 



to be related both to Assiminia in the Turbinidce, and to Lacuna 

 and Globularia in the Naticida. From the former it is distinguished 

 by its more globular form, and by the openness of the umbilicus, as 

 well as by the absence of any distinct shelly plate, adhering to the 

 body-whorl, within the aperture. From Lacuna it may be known 

 by the circumstance of the umbilicus being situated about the centre 

 of the aperture, instead of near its summit, and by the same 

 absence of a shelly plate. From Globularia it is distinguished by 

 its more lengthened form, less concave inner lip, and by the absence 

 of a thickened belt at the base of the body whorl. 



Mttilus nigee, Benson. 



Testa oblonga, trigona ; cardine unidentato ; natibus subincurvatis, 

 decorticatis, sub epidermide albis, marginibus purpurascentibus; intus 

 margaritaceo-splendida, margine purpureo. Long. 3.4 poll. Lat. 1.7. 



It is punctuate in the interior, especially near the beaks. There 

 are Flustra on all the specimens, leading to the supposition, not- 

 withstanding their nacre, that the habitat is marine. 



Dreissena PTjRPUitAscENs, Benson. 



Testa oblonga sub-quadrata, radiato-plicata, sub epidermide albo 

 purpureoque ornata, intus margaritacea, epidermide brunneo, apice 

 subincurvato, compressiusculo. Long. 1.5, Lat. 0.8 poll. 



The anterior margin is minutely toothed. The posterior muscu- 

 lar impression is curiously honey-combed, and the whole of the 

 interior is strongly punctuate at nearly equidistant points. The plica? 

 or raised striae are strong within a short distance of the beaks and 

 along the anterior side of the umbonal slope, but become obsolete 

 on the rest of the shell. The epidermis is scabrous and covered 

 with a minute weed, which looks like a fresh- water production. 

 The septum at the beaks refers this shell to Dreissena of Van 

 Beneden, which includes the flnviatile species polymorpha of Europe. 



" Dr. Cantor never saw those muscles alive, but found the empty 

 shells about the houses at Tinghae. The Chinese said that they 

 were found in great numbers in the canals close to the sea, but only 

 in winter, when large supplies are brought to market. They also 

 asserted that they attain upwards of six inches in length." 



