4 GILBERT C. BOURNE. 



processes bearing projectiug sense-papilla3, such as have 

 been described by Vayssiere in Scissurellacostata. The 

 cephalic tentacles are moderately long, reaching in their 

 contracted state as far forward as the end of the snout. They 

 are fringed with a large number of small, conical sense- 

 papillte, which, in Incisura, are not scattered all over the 

 surface of the tentacles as figured by Vayssiere for 

 S. costata, but are arranged in two multiple rows on the 

 inner and outer margins of each tentacle (fig. 27), somewhat 

 like the pinnules on the tentacles of an Alcyonarian polyp. 

 The structure of these sense-papillae will be described further 

 on. The eyes, which are closed and provided with a cornea 

 and lens, are situated on prominences at the outer sides of 

 the bases of the tentacles. Just below and behind the 

 tentacle of each side is a short sub-ocular tentacle which 

 does not bear sense-papillae like the cephalic tentacles, but is 

 richly ciliated and glandular in structure. In the single male 

 specimen of which I have cut sections, the sub-ocular tentacle 

 of the right side is somewhat enlarged, spatulate in form, 

 and more abundantly provided with gland-cells than in the 

 females. In all the females I have examined the sub-ocular 

 tentacle of both sides is digitiform. 



The foot, as is shown in fig. 1, is rather short and triangular 

 in shape, the apex of the triangle being posterior. In shape 

 and in the size of the broad, creeping sole it differs consider- 

 ably from the narrower elongated foot of S. costata and 

 S. crisp at a. The epipodium begins as a low ridge in about 

 the middle third of the foot, and increases in size posteriorly. 

 As described b}?^ previous authors it bears three moderately 

 long epipodial tentacles on each side of the body towards the 

 posterior end of its course. These tentacles bear lateral rows 

 of sense-pjipillee exactly like those of the cephalic tentacles, 

 but there are no ventral cirrhi in connection with them as 

 in S. costata. The epipodial folds meet posteriorly above 

 the posterior end of the foot, and just dorsal to and in front 

 of their union is a muscular opercular lobe bearing the 

 operculum. The last-named structure is small, horny, and 



