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nerve arises first by a primary dorsal root, then by a secondary ven- 
tral root, finally by tertiary ventral roots. The dorsal root de- 
generates and has absolutely no representative in the 
adult, the secondary and tertiary ventral roots alone remaining. 
The facial on the other hand arises by single primary dorsal and 
ventral roots, both of which persist throughout life — the 
dorsal becoming closely related (but not in Chimaera) 
to the trigeminal nerve. Hence the mistake, made by Srannius 
(10), GEGENBAUR (11), JACKSON and CLARKE (12), and others of re- 
garding the superficial ophthalmic and buccal divisions of the facial 
as branches of the trigeminus. Hence also it follows that the trige- 
minus of cartilaginous fishes must arise by ventral roots. Van WIsHE 
further states (p. 27) that the superficial ophthalmic and buccal 
divisions of the facial have arisen by the dichotomous splitting of 
one dorsal nerve, and Dr. BEArp, whose magnificent collection of 
Elasmobranch embryos renders any statement of his on the subject 
of unusual importance, informs me that MARSHALL and SPENCER’S 
paper is a perfectly correct statement of the facts. Mr. CoLLINGE 
(p. 882) states: “Ewart, who was the first to carefully investigate 
this matter in the Elasmobranchii, has shown that the whole system 
is innervated by the facial complex, ramus oticus and vagus, ‘the 
fifth taking no part in innervating the canals’.” This is certainly not 
a correct statement of the case. If MARSHALL and SPENCER’s paper 
had never been written, at least EwArr’s superficial ophthalmic and 
most probably his buccal divisions of the facial would have been de- 
scribed as branches of the Vth (see particularly, Ewart [6], p. 528). 
Now as to Mr. COLLINGE :— 
Our author states that his results “are exceedingly interesting 
and quite unlike what he expected”; and again “he expected to find 
an innervation solely from the facial”; and later “it will thus be seen 
that the facial nerve is almost entirely replaced by the trigeminal, 
not unlike the condition he had previously described in the Physo- 
stomosus Teleostei” 1). After the first two statements, to which all 
zoologists will cordially acquiesce (cf. BAsarorp Dean [14], p. 275), 
the last comes somewhat as a shock, and I cannot help thinking 
that Mr. Conuinee hardly realises the gravity of his statements. To 
link together the Holocephali and the Teleostei in such an important 
connection as their cranial nerves, is only justifiable after a much more 
1) But compare the very different account given of this group by 
Porrarp, Zool. Jahrb. (Morph.). Bd. V. | 
