356 General Notes. 
Muscies oF Moxuuscs.—There are frequently described in 
molluscs striated muscles, sometimes of a peculiar type. Müller 
and Keferstein have described them in the heart of Cephalopods 
and in the pharynx of the Cephalophora ; Blanchard, in the adduc- 
tors of Pecten, and Paneth, in the fins of Pteropods and Heteropoda. 
Schwalbe has described in the adductors of the lamellibranchs and 
elsewhere muscles with a double oblique striation, while, before. - 
him, Mettenheimer, Wagener and Margo had referred to the same 
appearance as spiral striation. Lately, Fol (Comptes Rendus, Jan. 
23,1888) has investigated the same subject, and concludes that true 
striated muscles do not exist in any mollusc. All cases reported as 
such, in reality, consist of smooth fibres, around which fine fibrils 
are rolled in a spiral manner, this being the case in all the special 
-instances noted above. The method employed by Paneth (glycerine 
and nitric acid) produced such contraction that the spiral fibrillee 
really appeared transverse. of the molluscan muscles are of the 
smooth type; but these are to be grouped in two sub-divisions— 
that already mentioned, and that in which the fibrille are straight. 
The latter are the more abundant. Judging from their distribu- 
tion, the spiral type are of value where a rapid contraction is 
needed, 
THE Primary Groups OF MAIL-CHEEKED FISHES. — 
recent study of the structural characteristics of the mail-cheeked 
fishes has led to some interesting and unexpected results. The 
genus Dactylopterus, which has been almost universally closely 
associated in the same family with Trigla or Peristedion, an 
especially with the latter, was found to differ very widely. The 
relative proportions of the spinous and soft parts of the dorsal fin, 
to which so much value has been attributed by Dr. Giinther, proves 
to be of comparatively slight importance. All the families recog- 
nized by Dr. Günther, except that of the Heterolepidotide, are 
very unnatural combinations of dissimilar groups; most of those 
recognized by myself are amply justified by anatomical evidence, 
but several others must be added to the list. 
The genius of Cuvier, manifested in the perception of the rela- 
tions of forms differing so much in superficial characteristics as do 
the mail-cheeked fishes, is justified by a detailed study of the various 
constituents of that group. The course of Günther and his fol- 
lowers in disintegrating it, widely divorcing its constituents, an 
associating its fragments with dissimilar forms, was a deci edly 
retrograde step. Nevertheless, although the group is one whose 
members are genetically connected, the diversities of structure are 
too great to allow of their retention in one family or even super- 
family. They must be distributed into four (and ultimately more) 
superfamilies; those nów determined are the So the ) 
Cottoidea, the Trigloidea, and the Dactylopteroidea. veral forms 
