780 MR FRANK J. COLE 
true (soft) cartilage. The bar comes to the surface of the M. longitudinalis lingue in 
the mid-dorsal line, and extends in front between the posteriorly diverging halves of the 
M. copulo-copularis, with which, however, it is not connected. The whole edge of the 
bar and the lateral portions of its ventral surface provide an origin for some of the 
dorsal fibres of the longitudinalis linguee, whereas the median portion of the ventral 
surface gives attachment to the M. perpendicularis. Behind the latter muscle the bar 
sends downwards and backwards in the mid-longitudinal vertical plane a thin tough 
sheet, the two sides of which give origin to a considerable bulk of the fibres of the 
longitudinalis lingue, and which separates the two halves of this muscle in the middle 
line posteriorly. In front of this they are separated by the perpendicularis. This 
tough sheet in the specimen dissected consisted of hard pseudo-cartilage like the 
remainder of the bar, but in a series of sections of a 25 cm. Hag it was composed of 
connective tissue. It thus seems to chondrify as the animal grows. The superior 
chondroidal bar is a broad dorso-ventrally compressed plate rounded behind and pointed 
in front, 11 mm. long and 5 mm. at its widest part. 
In Bdellostoma, according to AyERS and Jackson, there is a difference of some 
importance. oth bars consist of the hard pseudo-cartilage, similar to that of the 
posterior segment of the basal plate, and, to quote AYERS and Jackson, “are not, 
therefore, to be regarded as skeletal derivatives of the visceral or branchial arches, but 
simply as chondroidal modifications (7.e. condensations of connective tissue) in the 
muscular fascia” (op. cit., p. 212). Now we have seen that the inferior chondroidal bar 
of Myxine is composed entirely of typical hard cartilage, and further, that the superior 
bar may contain nodules of true soft cartilage, as in the so-called branchial arches. We 
must therefore conclude either that these bars in Myxie and Bdellostoma are not 
homologous, which is surely incredible ; or that the histology of the skeleton, as we have 
the best reason for supposing, is but an equivocal morphological guide. There are, 
however, strong grounds for believing that Ayers’ and Jackson's description of the 
inferior bar is inaccurate ; for J. MUuier’s description of the two bars in Bdellostoma 
agrees exactly with mine in Myaine, and W. K. Parxsr, who seems to have missed the 
superior bar altogether, describes the inferior bar both of Myaine and Bdellostoma as — 
formed of ‘hard cartilage” and colours it green in his figures. 
L. THe Brancwiat SKELeTon. (Figs. 11-15.) 
This was first described for Myxine by Burne,* having previously been missed by 
J. Muxyer (who first found it in Sdellostoma, but whose language is ambiguous as 
regards Myxie) and W. K. Parker. SCHREINER? notes its presence in Myaine; and 
it 1s, in fact, quite easily seen by any one accustomed to careful dissection. On the other 
hand, Burne failed to find the so-called “ gill bars” of AyERs and Jackson in Bdellostoma, 
and I am able to supplement his description of Myavine in several important respects. 
* P. Z.S., 1892, p. 706. + Bergens Museum Aarbog, 1898, No. 1, p. 6. 
