Annals of the South African Museum. 



each side ; apical claws slender, each with two hair-like denticles at 

 the base. 



Colour bright red. 



Length of shell reaching about 1 mm. 



Remarks. I have failed to detect any reliable difference between 

 the above-characterised form and typical specimens of T. sordid/us 

 taken in Norway. It is the first described species, and accordingly 

 ought to be regarded as the type of the present genus. 



Occurrence. This form developed in great numbers in the bottom - 

 deposit of some of my aquaria prepared with mud from 'the neighbour- 

 hood of Borgvliet. Most of the specimens were covered by a thick 

 coating of mud so firmly adhering to the shell that it was a matter 

 of no little difficulty to remove it, in order to get a correct view of the 

 animal. 



Distribution. Throughout Europe, North and South America, 

 Sumatra, Australia. 



FAM. CHYDOKIDAE. 



GEN. !). LEYDIGIA, Kurz. 



Remarks. This genus was established in the year 1874 by Kurz, to 

 include the peculiar form described by Fischer as Lyticeus acanthocer- 

 coides. Another form belonging to this genus was recorded by 

 Leydig, but erroneously identified by that author with Lynceus quad- 

 rangularia Miiller. To these two northern forms a few exotic species 

 have in recent times been added. The genus may be easily recognised 

 by the broadly expanded, almost trigonal shell, and by the largely 

 developed caudal piece, which in shape and armature somewhat recalls 

 that in Ihjucnjptus. Three well-defined species of this genus belong 

 to the fauna of Cape Colony, two of them being new to science. 



26. LEYDIGIA MACRODONTA, n. sp. 

 (Plate XXXVII, figs. 2, 2 a, b.) 



Specific Characters Female. Shell, seen laterally, broadly tri- 

 angular in outline, and considerably expanded behind, dorsal margin 

 nearly straight in its posterior part, but anteriorly forming a quite 

 even curve until the tip of the rostrum ; upper posterior corner well 

 marked ; hind edges of valves very oblique and almost straight, 

 passing into the inferior ones by a very strong curvature. Head 

 slightly procumbent, with the rostral projection scarcely curved, and 



