Prof. P. M. Duncan on the Salenidse. 247 



further on, and after the examination of the morphology of 

 the other recent forms. 



To resume the morphology of Salenia 2-)rofundi. The 

 peristome is moderately large and wide, and it bears the ratio 

 of l*75*to 2"7o to the widest part of the test. It is circular 

 in outline ; and tliecuts for the gills are small ; moreover the 

 edge of the test is slightly everted so as to form a faint mar- 

 ginal ridge. The remains of the gills are to be seen in the 

 specimen ; and they are bifid, appearances of a trifid arrange- 

 ment being visible in some (fig. 10). The actinostome (the 

 opening for the teeth), circular in outline, is at the end of a conical 

 prtjjection of the buccal membrane ; its edge is plain, and there 

 arc faint indications of imbrication close to it, but not else- 

 where on the membrane. This membrane has a rather large 

 surface ; it is plain, except close to the actinostome, and pre- 

 sents a remarkably glistening apjjearance interrupted by 

 minute pigment dots ; and this appearance is produced by its 

 containing -in its upper layers minute geometrical scales of 

 carbonate of lime separated by less-silvery-looking tissue, and 

 the whole speckled with dark purple pigment. This silvery 

 plain surface reaches to the edge of the peristome, and it 

 becomes continuous with the superficial ornamentation of the 

 test, which, without having the separate microscopic plates, is 

 white, glistening, and pigmented. 



Moreover the membrane so covers the ten buccal plates 

 that their place can only be suggested by the presence of the 

 five pairs of buccal tentacles and their Associated pedicellariae: 

 it is continued up onto the base of each tentacle, and it gives 

 origin to the stalks of the pedicellariae (fig. 9). The buccal 

 tentacles in five pairs are situated at rather more than one 

 tliird of the distance from the peristome to the actinostome ; 

 and one pair is opposite to each ambulacrum. Each tentacle 

 has an elongate and elliptical sucker with fine radiating lines 

 of slight depression at the edge, and a stout stem, Avhich is 

 marked with transverse circular constrictions and also by a 

 few longitudinal strife which are continuous with those of the 

 edge of the sucker. Each pair of tentacles has two pedicel- 

 lariffi close to them ; and these are situated between and 

 rather internal to them. The pedicellaria^ are glistening and 

 icy in appearance ; the rather long peduncle is stoutish and is 

 swollen slightly here and there ; and at the free end is a 

 rounded knob for the articulation of the cavity of the head. 

 This is broad, tapering, short ; and the jaw-slit is short and 

 nearly free from any raggedness. The bifid nature of the 

 pedicellarige is seen in one instance where the head seized the 

 sucker of the neighbouring tentacle in its death-grasp. 



18* 



