226 PART II. SYSTEMATIC ACCOUNT 



ratio of 5 : 1. An annular groove runs behind the base of the tentacle, curving 

 slightly backwards on the dorsal side of the body (Fig. 1155). The protosoma 

 is tiny and the cephalic lobe conical and comparatively small. The mesosoma 

 narrows towards both ends and also in the middle, behind the bridle, 

 noticeable in side view (Fig. 115^4). The yellowish or dirty-brown keels of 

 the bridle are fused together dorsally but do not meet ventrally — the con- 

 verse of the usual situation (Fig. USA, B). The tentacle is rather stout, but it 

 is capable of great extension, and the large pinnules (up to 190/x long), which 

 characteristically begin almost at the base of the tentacle (Fig. 115.4), are 

 arranged in a single row, but with a slight tendency towards doubling up 

 (Fig. 115C). Within them the blood capillaries may be seen (Fig. 1155). 



The metameric region of the metasoma bears large, rounded and, 

 anteriorly at least, more or less paired papillae (Fig. MSA). In one individual 

 studied there were about 27-30 pairs, but in others there were many more. 

 The ventral sulcus of the metasoma is broad and the dorsal ciliated band 

 well-developed (Fig. 1 1 SB). The zone of thickened papillae remains unknown. 

 S. buccelliferum has three girdles of toothed platelets, the two in front placed 

 close together, with the third a considerable distance behind, after which the 

 trunk takes on the character of a postannular region (Fig. WSD). All the 

 girdles lie on muscular ridges and each consists of two halves. The ventral 

 ends of the first girdle are separated by a broad gap, while the dorsal ends 

 meet in the mid-line. The two parts of the second girdle, on the contrary, 

 meet in the mid-line on the ventral side, but are far apart dorsally (Fig. 

 MSE, F). The hindmost girdle hardly extends onto the ventral side at all, 

 and its two halves are located wholly on the dorsal side, where they almost 

 meet in the mid-line (Fig. 115G). The yellowish elongated toothed platelets, 

 arranged in a single row (Fig. 115//), are rounded at the ends and rather 

 strongly waisted in the middle, in consequence of which they take the form 

 of that type of biscuit known as langue de chat, whence is derived the name 

 S. buccelliferum [Latin buccella, a small mouthful, a morsel, whence late 

 camp-Latin, buccellatum, a soldier's biscuit \ferre to bear]. The front part of 

 each platelet is noticeably narrower than the hind part, and, as seen in profile 

 (Fig. 115/), the teeth are very long and thin. The pinched-in middle partis 

 free of teeth (Fig. 115//). The group of teeth in front of this bare patch, with 

 their points directed backwards, are characteristically well developed, but 

 both in size and in number they are considerably less than those of the back 

 half of the platelet. Most of the platelets are 16— 18/x long, with a few shorter, 

 12-14^, but occasionally one may come across under-developed platelets 

 only about 10/la long. Their greatest breadth (near the front end) is 4ju. The 



