BURNE : SOUTH AFRICAN ArLYSTID^. 55 



The shell (Figs. 6, 7) : Unfortunately the calcareous part was broken 

 to pieces, but the general shape can be recognised from the stout 

 periostracum. It is of elongated oval form, moderately convex, with 

 the beak strongly incurved, and with an upstanding reflected hood. 

 The sinus is short and moderately concave. 



Fig. 6. Fig. 7. Fig. 8. 



The alimentary canal : The jaws lie on either side just within the 

 mouth. They have an irregularly oval form measuring 3 hj 2 mm., 

 and are covered by chitinous hair-like rods -08 millira. in length, with 

 a pointed and slightly hooked free extremity (Fig. 8). 



The radula has tlie formula 22 : 1 : 22. The median tooth has 

 a central blunt cusp with denticulate edges, and two pairs of lateral 

 cusps. The lateral teeth have a long denticulate cusp towards the 

 median side, and upon the lateral side two smaller smooth cusps. 

 The teeth are relatively laige, being about equal in size to those of 

 T. operta, although the animal is much smaller. 



The alimentary canal otherwise closely resembles that of T. operta, 

 but the intestine is longer with similar though more pronounced coils. 

 The following measurements of the different parts may be noted: — 

 (Esophagus, 7mm. long by 1-5 mm. diameter; crop, 17mm. long by 

 7 mm. diameter ; gizzard, 4 mm. long, with two rows of thorn-like 

 chitinous teeth upon its inner surface. 



The opaline gland consists of a number of isolated follicles covering 

 an area of the body- wall below, and slightly posterior to, the genital 

 opening. It measures 6 mm. long, by 4 mm. broad, and is more 

 pointed behind than in front. 



Eeproductive organs : The only remarkable feature about these 

 organs is the absence of the seminal vesicle. The albumen gland also 

 is extremely small. 



The gill, mantle-cavity, kidney, pericardium, and heart show no 

 special features worthy of mention. The aortic appendage {crista 

 aorta;) is large and leaf-like. 



This specimen is of somewhat exceptional interest, for in its general 

 configuration, in the arrangement of the parapodia and mantle, and in 

 the position of the external openings, in fact, in nearly all its most 

 important external characters, it resembles the genus Paraplysia of 



