164 



MALACOLOGICAL NOTES. 



By E. R. SVKES, B.A., F.L.S. 



I. On a three-valved Ischnoehiton. 



The specimen now descriljed was collected by Mrs. A. F. Kenyon in 

 Victoria and presented by her, very recently, to the British Museum. 

 It is preserved in spirit and measures, when contracted, 13 by 8 

 millim. From the external appearance it appears to belong to /. 

 contractus (Rve.). 



The tail-valve occupies a space rather more than equal to that 

 taken by the head and median valves together. At the posterior end 

 the mantle is drawn up much as in Schi::ochifon, but this may be due 



Fig. I. — Three-valved Ischnoehiton. 



to contraction, or to the fact that the tail-valve has received some 

 injury. The middle valve has the lateral area on one side much 

 exaggerated and divided by a radiating line. The head-valve is 

 normal. 



Specimens of Polyplacophora, having less than the normal number 

 of valves, appear to be very scarce. Seven-valved specimens are 

 known, indeed there is one, a Cltiton, in the British Museum, but I 

 have never seen one with less than this number. 



2. On the occuprenee of Cryptoplax in South Africa. 



The genus Cryj/fojjlar, so far as known, ranges from the Philippines 

 to the Australian Province. The occurrence therefore at Umkomaas, 

 in Natal, of a specimen apparently belonging to that genus, is 

 of unusual interest. The single specimen, which was collected 

 by Mr. Burnup, and forms part of his collection, measured when 

 alive, apparently, about 14 millim. in length but was curled up and 

 shrunk in drying. 



The girdle shows no signs of pores but is densely clothed with 

 small spicules, forming bunches at the sutures. The valves, partly 

 covered by the girdle, are all in contact and have no intervening 

 area. The head-valve is granulose, while the other valves have an 

 almost smooth central area, and the lateral and median areas are 



