772 MR FRANK J. COLE 
‘‘dominant monster of the Hag.” It may be regarded as consisting of a linear series 
of three pieces—the anterior, middle, and posterior segments of the basal plate (b. p.*~*), 
Looked at from the side (fig. 1) the posterior segment is horizontal, whilst the two 
anterior segments constitute a dorsally inclined plane. 
The anterior segment is the most complex. It consists of three pieces—a median, 
the internal bar of the anterior segment (7. b. p.’), and two lateral, the external bars of 
the segment (e. b. p.’). The two latter, and to a slight extent the former, bear in front 
pads of soft pseudo-cartilage (uncoloured and obliquely striated in the figures) which 
contain nodules of true soft cartilage, especially near the dorsal border. The lateral 
labial cartilage (/. /. c.), composed of soft cartilage, courses downwards in a sigmoid 
twist over the dorso-external face of the large outer pad to merge gradually and 
without any break into the hard cartilage of the external bar, which extends a short 
distance in front of the internal bar. The anterior border of the latter, covered with 
a layer of smooth soft pseudo-cartilage, forms a concave pulley surface for the tendon 
of the M. copulo-glossus profundus (=the protractor of the dental plate—Avyers and 
Jackson), which tendon is shown cut across in fig. 10 (c.g. p.). This tendon passes 
forwards from its muscle wnder the internal bar, doubles round the pulley border on 
to its dorsal surface, and then courses backwards over the bar, to be inserted into the 
anterior arch of the dental plate. The dorsal surface of the imternal bar also bears a 
thick pad of soft pseudo-cartilage anteriorly, against which the dental apparatus glides 
backwards and forwards. Just in front of the posterior fenestra this pad thins down 
and splits into a paired structure, which assists in forming the angular depression in 
which the V-shaped dental skeleton works. The internal bar is composed entirely 
of hard cartilage except where it passes into the middle segment behind, and consists 
of one piece only; for whilst it thins down somewhat in the middle line, there is no 
break or even a change in the character of the cartilage. Posteriorly, there is a large 
elongated fenestra closed by fibrous tissue, and we find a zone of soft cartilage inter- 
posed between the internal bar and the hard cartilage of the middle segment. But here, 
again, itis a gradual transformation, and there is no break or suture between the two seg- 
ments. On the other hand, the external baris quite independent of the internal bar and 
of the middle segment, being separated from the latter by a pad of soft pseudo-cartilage 
(uncoloured and obliquely striated in figs. 10 and 1). A transverse section through the 
anterior segment of the basal plate shows that the three pieces form a deep crescentic 
trough which lodges the dental apparatus. The internal bar is slightly curved, with the 
concavity dorsal; and the external bar, separated from the internal by a fibrous packing, 
projects upwards and outwards (cp. fig. 1). 
The middle segment (b. p.”) is comprised of one piece of hard cartilage, but in the 
middle line it is very thin and there consists of soft cartilage (fig. 10). There is, how- 
ever, certainly no break or suture. In transverse section the cartilage is seen to be 
very thick laterally and to form a shallow cup, with the concavity dorsal. In order to 
provide a groove for the keel of the dental skeleton, and behind for the retractor tendon, 
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