320 PROCKEDINGS OF THE MALACOLOGICAL SOCIKTT. 



really represent is a nice puzzle in identification and nomenclature, 

 a subject for a future paper which I trust Mr. Ponsonby will 

 eventually give us. I therefore restrict myself to a description of 

 the animals, and shall say nothing of the shells. 



Macrochlamys, sp. A ; Mauritius. PI. XVIII, Figs. i-iv. 



Animal with a long foot, pale grey in colour, right shell-lobe very 

 short and blunt (Fig. i), recalling that of M. pedina of Bombay,^ the left 

 (Fig. ir) feebly developed, triangular on a broad base ; dorsal lobes as 

 usual, the left in two parts, the posterior the smallest ; peripodial 

 grooves well marked, the fringed margin with its groovings numerous 

 and set close together (Fig. iv) ; mucous gland at extremity of the 

 foot large, and with an overhanging lobe ; sole of foot with 

 a central area. 



The genitalia (Fig. iii). — The araatorial organ is very large, long, 

 and cylindrical, tapering gradually with the end, terminating rather 

 squarely where the long retractor muscle is attached. 



The penis has a large coiled caecum, where it bends on itself. The 

 retractor muscle is attached to it in the usual way. At the junction 

 of the vas deferens with the penis a long flagellum is given olf ; the 

 vas deferens itself is short, and thicker than usually seen, and it joins 

 the prostate just above a swollen ochre-coloured portion of the vagina 

 duct. Just below this is the spermatheca, very long, ample, and 

 swelling slightly towards the free end. The jaw is dark- coloured, 

 solid, strongly arched, with a projection on the cutting edge. 



The radula has the formula 46 : 20 : 1 : 20 : 46, or 66 : 1 : 66, 

 altogether 132 teeth in the row. The central tooth and admedians 

 are rather narrow, sharply pointed teeth, with a cusp low down on 

 the outer side ; these at the twentieth tooth gradually merge into 

 bicuspid laterals, the cusp well below the point, and as far as the 

 outermost small teeth they never become evenly bicuspid. 



Of the rest of the anatomy there is nothing specially noticeable in 

 the characters described. This species agrees in every way with an 

 Indian Macrochlamys of typical species of Lower Bengal, such as 

 indica, G.-A., from Calcutta, and in this connection even the type of 

 shell- sculpture is the same, as well as the general form of the shell, so 

 much so that I looked up the formula of the radula of indica to see 

 what correspondence there might be ; it differs very materially, being 

 34 : 2 : 9 : 1 : 9 : 2 : 34, or 45 : 1 : 45, or with only half the 

 number of large admedian teeth. 



Maceochlamys, sp. B ; Mauritius. PI. XVIII, Figs, v-vii. 



Animal not quite so grey as species A, but the membrane covering 

 the branchial cavity is blacker, and freckled with the same colour, not 

 seen in the other two specimens. 



The fringe on the peripodial margin is in wider segments, and the 

 longitudinal grooves leading upward from the peripodial grooves to 

 the keel of the foot are very strongly marked. The mucous pore 



' Vide L. and F.W. Moll. lud., pi. xxxiii, ti";. 1. 



