1887] ae Zoology. 1033 
between the segments of the muscle of the lateral line a series of 
vertical cartilaginous plates are developed, extending backward 
and outward. They are irregularly triangular in outline, and 
the apex of the triangle, which is directed forward and inward, 
overlaps the distal extremity of the epicentrale. These carti- 
lages seem to be evidence that a process of differentiation is going 
_ on in the shad similar to that which resulted in the differentiation 
of the sense organs of the head, and give support to the theory 
that these are derived from integumentary sense organs allied to 
_ those of the lateral line. 
= A consideration of their relation to the other skeletal elements 
of the abdominal segments suggests that the foremost visceral 
aches are not homologous with the branchial arches, but may 
long to a series including the extra-branchials of Parker, the 
_ Sapula portion of the pectoral arch, and the epipleurals. 
_,, they also suggest an origin for the free portion of the paired 
i limbs from a ventro-lateral series of sensory organs, similar to 
f those seen in amphibian larvæ which lie in a line connecting the 
fore and hind limbs. 
Such a development might afford some explanation of the 
“phalic fin present in some elasmobranch fish either as a survival, 
Be teversion.— Fanny R. M. Hitchcock. 
; ot THE Epitors OF THE NATURALIST: 
ko Owing to the failure of the corrected revise to reach 
ue 
p Publishers, my article, “ Remarks on Classification,” in the 
Ctober number, requires some comment: : 
i On page ots, last paragraph, the words neither tubular nor 
», &00ved should be never tubular. 
Near the bottom of the Table, the equivalent of Stereo- 
muta should be “ invertebrates —tunicates. i 
Poh att about the middle of the Table, under Monoccelia and 
ycælia, the words axon unsegmented and axon vertebrated 
d 
cal News.—Ca:tenterates.—Mr. Richard Rathbun 
a with notes, the species of the genus Madrepora in 
