NOTES AND EXHIBITS. 651 



yellow epidermis. The umbilicus in the young specimens is quite 

 open and is seen to penetrate deep into the shell; in the adult 

 specimens the umbilicus is not so decidedly covered by the 

 dilated adnate adherent columella as in typical adult speci- 

 mens of the species which is very smooth, quite unlike the 

 characteristic coarse!}- granulated columella of Thersites nigrila- 

 bris of E. von Martens, described in 1869 ( = T. Edirardsi, Cox, 

 described in 1868, p. 110, Appendix Mon. Aust. Land Shells). T. 

 ni(/rUabris, however, has riot always a very dark peristome 

 (" nigrum " in the original). I have very fine living specimens of 

 it in which the peristome, the expanded callus over the umbilicus, 

 and in fact the whole labrum is perfectly v/hite, and there is not 

 nearly so marked a subsutural dark band as there is in the 

 .specimens now exhibited of this varietal form of T j}acJ/i/sfi/Ia, 

 the apical whorl is quite smooth, but on the upper parts of the 

 third and fourth and part of the last whorl faint rather waved or 

 wrinkled strife are plainly visible running parallel with the 

 sutures. 



An illustrative series of specimens, adult and young, was 

 exhibited. 



Dr. Cox also exhibited very fine specimens of what he looked 

 upon as varieties of Thersites biparlita, Ferussac, smaller than 

 typical specimens, with the base very dark, and with a very dark, 

 rather narrow band running parallel with the suture, the lip 

 of the shell also inclined to a carnelian-pink. These specimens 

 might lead off to what had been described as Thersites Beddomei, 

 Braz., but the shell in question was found with larger specimens 

 which gradually passed into the typical form. To illustrate the 

 genus a large typical pair of T. bipartita were exhibited, with a 

 pair of the same quite devoid of a dark base or coloured sutural 

 band; also a pair subangulate at the periphery of the last whorl 

 and depressed, from Cairns, of large size; likewise a pair of the same 

 of smaller size, ver}' much resembling in colour, &c., the smaller 

 forms of Nanina ovum from the Philippine Islands ; and two 

 pairs of a smaller variety, much more depressed than the type, 



