88 



Recorded by Hincks from the Mergui Archipelago (W. of the Malay Peninsula); by 

 Kirkpatrick from the Tizard Bank (between the Philippine Is and Cochin China) and Torres 

 Straits, and by Miss Thornely from Ceylon. 



Tliis species is obviously a common Ctenostome in the region investigated by the 'Siboga', 

 as is evident from the list of localities given. It has been well described and figured by Hincks, 

 to whose account I have little to add. The number of spines at the distal end of the zooecium 

 is nearly always four, the number recorded by Hincks. But in one case (38. K.) I find a lar°"er 

 number in some of the zooecia, indicated by their basal segments, which may be as many as 

 eight. Hincks has given a "correction" (op. cit., foot-note on p. 127) of the position of the 

 spines shown in tvvo of his figures-, stating that these originate from the margin of the distal 

 end of the zooecium. The 'Siboga' specimens show, however, that there was no inaccuracy in 

 the figures in question, but that the spines may appear to originate from the margin or more 

 proximally, according to the state of protrusion of the kamptoderm. 



Hincks has described a peculiar arrangement, which I can confirm, of the supporting 

 ribs of the collar. These are spirally disposed in the proximal part of the structure (fig. 9), 

 but become straight distally. By focussing down through the spiral part it can be seen that 

 the ribs of the opposite side cross those of the side which is uppermost; indicating that the 

 direction of the spiral is the same all round the collar. 



Hincks has stated that that the polypide is "small, and of very simple structure"; and 

 further that "there seems to be no tracé of a gizzard". I cannot agree with either of these 

 statements. The polypide is not simpler in its structure than is that of other Ctenostomes. The 

 vestibule is of great length (fig. 10), in correlation with the great development of the collar; 

 and it is retracted by strong parieto-vaginal muscles. The tentacles are bent in retraction ; and 

 the oesophagus in this position passes distally, being, moreover, of considerable length. At its 

 distal end, this limb of the alimentary canal passes proximally and forms a well marked gizzard 

 before opening into the stomach. It need hardly be remarked that these relations would be 

 altered in the protruded condition of the polypide. 



The membranous "aperture" varies in length. In the specimen shown in fig. 10 it is 

 shorter than usual ; and three groups of parietal muscles are visible, on each side; their fibres 

 being inserted into the membrane of the aperture, the function of which is thus, as might have 

 been expected, to permit the protrusion of the polypide. 



The zooecia are usually from 4S0 u. to 550 ij. long, and as much as 180 \j. in greatest 

 breadth. The collar shown in fig. 9 is 460 u. long and 1 30 y. broad at its distal end. 



The species which has been described by Osburn l ) as Hippuraria armata (= Vesicu- 

 laria armata Verrill, 1874), from the Woods Hole Region, Mass., appears to me to be a 

 Buskia and to be nearly related to B. sctigera. It may be noted that Osburn describes a 

 distinct gizzard. It is pointed out below (p. 90) that Busk's original account of Hippuraria 

 was based on a misconception, and that there is no reason for separating that genus from 

 Triticclla. 



I) OsiiURN, R. C, 1912, "Biy. Woods Hole Region", Buil. Bureau Fisheries (Washington), XXX, p. 256, PI. XXIX, figs S4, 84^. 



88 



