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Nachdruck verboten. 
The Extrabranchial Cartilages of the Elasmobranchs. 
By Eruetwrn Foore, student at Smith College. 
With 4 Beare 
In a recent paper‘), Wuire called attention to the omission of 
any mention of the upper extrabranchial cartilages of the dogfish in 
MARSHALL and Hurst’s description?). There is no reference at all 
to their existence in the skate in T. J. Parker’s “Zootomy” *), although 
the labial cartilages are there described. Moreover, in the work of 
W. K. Parker and G. T. Berrany on the Morphology of the Skull, 
this statement is made concerning the dogfish‘): “Four extrabranchial 
cartilages, parallel to the ceratobranchials are superficial to the corre- 
sponding sets of branchial rays”. Not only is the fact here ignored 
that there is a dorsal set running parallel to the epibranchials as 
well as a ventral series parallel to the ceratobranchials, but in sum- 
ming up “the chief points in which the skate’s skull differs from that 
of the dogfish”, the writer emphasizes “the absence of the extra- 
branchial cartilages” °). 
In a recent dissection of several species of the skate, I found 
these cartilages present: five dorsal and five ventral, in association 
with the hyoid and the first four branchial arches (Figs. 1, 2). These 
commence at the junction of the hypo- and ceratobranchials, connected 
with them by a membranous tissue, and curve up and over each gill 
plate, at the same time lying directly under the muscle bands. 
In Raja erinacea the extrabranchials are free and independent 
structures like those of the shark, except for a slight connection of 
the bases of the third and fourth on the dorsal side, a connection 
which is probably variable, and also an occasional fusion with the 
1) Anatomischer Anzeiger, Bd. 12, No. 6. 
2) MarsHatt and Horst, Practical Zoology, 4. Edit., 1895, p. 228. 
3) T. Jerrrey Parker, A Course of Instruction in Zootomy. Mac- 
millan & Co., 1893. 
4) W. K. Parker and G. T. Berrany, The Morphology of the Skull, 
Macmillan & Co., 1877, p. 39. 
5) Idem, p. 41. 
