86 
UKOHGE E. NICHOLES. 
Of adult inatei-ial, Sargeut states that the hiiidev part of 
tlie spinal cord of a single specimen of P. inarinus was 
alone examined. From the account which he gives of the 
preparation of the material, I suspect that the actual sinus 
terminal is was, partially at least, destroyed, for, as I have 
already pointed out, the hiuder wall of the terminal sinus lies 
so closely (in P. f 1 u v ia t i li s) beneath the skin that the removal 
of that and the adjoining muscles without injury to the sinus 
ter in i n al is is a matter of extreme difficulty. In this suspicion 
I am confirmed by the fact that Sargent offers no description 
of the terminal chamber, while his figure (’04, pi. i, fig. 3), 
which professes to represent the terminal sinus, clearly does not 
do so. 
A careful study of Sargent’s work shows that, apart from 
this single tail of Pe t ro m y zon m ar i n u s, he nowhere records 
the examination of the condition of the sinus terniinalis 
in any other adult vertebrate. 
Nevertheless, on the strength of an examination of the 
condition of this single, almost certainly datnaged specimen, 
he twice ventures (’00, ’04) to controvert the account given 
by Studnicka of the mode of ending of Reissner’s fibre in 
Petromyzon and Myxine. He says (’04, p. 160), “ Stud- 
nicka’s statement that the end of Reissner’s fibre passes out 
of the sinus of the ventriculus termiualis and into the sur- 
rounding lymph-space is so at variance with all my 
observations that I must believe the appearance he so 
interprets was accidental and due to the disturbed and 
abnormal condition of the fibre in his preparations.” (The 
spaced type is mine.) 
As a matter of fact, the account given by Studnicka, which 
was based on the study of a large number of series of sections 
of several dilferent species, is substantially correct so tar as it 
goes. It is true that the coiled condition of the fibre is 
pi’obably not normal but due to the recoil of the fibre following 
some breakage. It is nevertheless a condition very frequently 
to be observed. Whether, in the case of Studnicka’s material, 
this breakage was due to the cutting of the fibre in the fresh 
