770 MR FRANK J. COLE 
lateral labial itself, and shows in the sections as it approaches the labial some nests of 
hard cartilage. The stout base passes downwards and forwards, and lies within the 
contour of the body, forming more than half the length of the cartilage. The tentacle 
itself in the living animal is either almost perpendicular, or it can be rotated forwards ; 
hence the inclination of the external portion of the cartilage is subject to muscular 
control, and consequently varies in preserved material. The cartilage of the third 
tentacle is the longest ofall. After receiving it the lateral labial, connected by ligament 
in Bdellostoma with the tip of the cornual cartilage, according to J. MULLER, passes at 
first backwards, downwards, and inwards in a gentle curve, until it almost reaches the 
median plane, and thus arrives at the level of the pad of soft pseudo-cartilage at the anterior 
end of the basal plate. Here it makes a sudden downward and external sigmoid twist 
over the outer surface of the above pad, to fuse with the external bar of the anterior 
segment of the basal plate, as described elsewhere. Hence the lateral labials and basal 
plate form a cartilaginous circle round the mouth that is only broken for a short distance 
in the mid-dorsal line. 
The cartilage of the second tentacle (2), morphologically the first, is connected with 
the first by ligament in Bdellostoma, according to J. MULLER. On entering the body 
it passes at first straight backwards but soon takes a sharp bend inwards and downwards, 
underneath the nasal tube, to fuse with its fellow of the opposite side, and in that way 
to form the median suwbnasal cartilage or bar (sn. b.) passing backwards in the middle 
line underneath the nasal tube (fig. 2). In Bdellostoma the conditions are apparently 
somewhat different, the cartilage passing gradually into a transverse bar placed at right 
angles to the anterior extremity of the subnasal bar, and which AveErs and Jackson call 
the transverse “labial” cartilage. J. MULLER figures the transverse labial in Bdellostoma 
as suturally distinct from the subnasal bar, and in his description he says it is ‘‘ strongly 
connected” with the latter bar. AYERS and Jackson confirm this, and state that the 
‘transverse labial cartilage is attached to the anterior end of the subnasal cartilage.” 
PaRKER also figures it as distinct from the subnasal. Nrumayer’s figure of Myaine 
certainly allows a transverse labial to be delimited, and I find his figure to a certain 
extent confirmed by the sections of the 6°5 cm. Hag, and also by the sections of a very 
small My«ine kindly presented to me many years ago by Mr J. T. CunnineHam.* 
According to NruMayeEr’s figure, and the figure and description of PoLLarp,* there is, 
as I find also, no break between the skeleton of the tentacles and the subnasal bar, and 
it is difficult to escape the conclusion that this must likewise apply to Bdellostoma, in 
spite of the concensus of opinion above. The subnasal bar being thus formed by the 
fusion of the cartilages of the second pair of tentacles, is composed at first of soft 
cartilage. It soon flattens out so as to become narrow from side to side and deep from 
above downwards (cp. figs. 1 and 2). It lies a short distance below the nasal tube, 
* J have no actual record of the size of this specimen, but it would be about 10cm. I have already referred to it 
as the 10 cm. Hag. 
+ Anat. Anz., ix., p. 351; and Zool, Jahrb., Anat. Abt., viii. 
EAP. 
