774 MR FRANK J. COLE 
to them.* Finally, there are indications of a division of the middle segment into four 
pieces. PARKER also describes the two anterior segments of bdellostoma as consisting 
of six pieces “all connected together by tracts of soft cartilage,’ but he also quite 
erroneously makes the same statement with regard to Myaime, although it is contra- 
dicted by his own sections, which he misinterprets. PARKER entirely missed the 
lateral labials in Myaine, and failed to observe their correct relation to the anterior 
seoment of the basal plate in Bdellostoma. P. FUrRBRINGER also describes six pieces 
in the first two segments of Myxime; but his paper is not directly concerned with the 
skeleton, and his mind was evidently prejudiced by J. MULuER’s work. NerumMayer’s 
description and text-figure of Myaine, as far as they go, agree exactly with mine. 
In this connection I felt it important to examine very carefully the condition of the 
basal plate in Dr Brarp’s sections of a 6°5 cm. Hag, and found that it agreed absolutely 
with the condition described above for the adult—z.c. the anterior segment consisted 
of three pieces and the middle segment of one, nor was there any difference in the 
connections between these parts and in the distribution of the hard and soft cartilage. 
We can therefore only conclude either that the basal plate of MWyaxine differs in some 
important respects from that of Bdellostoma, or that the latter has still to be accurately 
described. I am convinced from my dissections, and from the examination of three 
series of sections (apart from those of Dr BEarp’s small Myaine), that the basal plate 
of Myzxine is here correctly described for the first time. 
I. SKELETON oF THE DentTaL Apparatus. (Figs. 7, 8, 9, and 1.) 
This portion of the skeleton has been picturesquely described by Parker as a 
“curious apron with slits in it and short strings projecting from it.” The teeth are 
laid on a somewhat complex skeletal framework, bent up from the middle line at an 
angle so as to form a V-shaped figure in transverse section. Its natural position—or, 
rather, one of them—in longitudinal space is seen in fig. 1 (a. d. p., p. d. p.). The whole 
apparatus, however, slides backwards and forwards in the trough formed by the basal 
plate, as already described, being drawn forwards by a protractor muscle, the copulo- 
glossus profundus (c. g. p.), and withdrawn by a retractor muscle, the longitudinalis 
linguee (/. /.), the tendons of which muscles only are shown in the figures. The teeth as 
a body thus move backwards and forwards, so that the Hag rasps its way into the body 
of its victim ; and not only this, but the whole apparatus with the teeth can be actually 
protruded entirely out of the mouth. This was first observed by Gunner, who 
described and figured the everted teeth in 1766. His statements were stoutly con- 
troverted by J. Mtiuer, who, on purely anatomical grounds, asserted that Gunwnur’s 
“entirely inaccurate.” I can, however, with other observers, fully confirm 
this old writer, for I have repeatedly observed the living Hag protrude its teeth in the 
way described, and have succeeded in preserving several with the teeth out. By this 
work was 
* This agrees with J. MULumr’s figure and description. Nevertheless I doubt it. 
