152 Journal of the Asiatic Society of Bengal. [N.S., XV, 1919.] 
single, or branching appendicula from mere projections of the 
wall of the placental.cord. It should, however, be noted that 
though we have a nearly complete series in the development 
of the long appendicula, this does not give us any clue as to 
the origin or evolution of these structures, nor does it indicate 
any near relationship amongst these forms, because in the spe- 
cies with the best developed appendicula the placenta i is of the 
most primitive and least evolved type and vice versa. Indeed 
the last mentioned fact seems to show that the forms with less 
highly organized type of placenta requiring some other mode of 
absorption of food have developed these additional structures 
or appendicula, which under these circumstances would be of 
the a of acquired or adaptive structures 
Branchial-filaments.—In the early stages of the intra-uterine 
embryos 0 erg many Batoids, large numbers of delicate and much 
elongated branchial- filaments are seen protruding out of the 
branchial openings of the embryos. These filaments are the 
greatly elongated gill-processes, coming out of all the gill-slits 
except the spiracles. In some cases they are so numerous as 
to form about one-third the mass of the whole embryo. In the 
later stages the branchial clefts are tightly closed and. there 
are no filaments, these apparently having atrophied long before. 
These structures have been called by such diverse names as 
branchial or gill-filaments, external gills or gill-filaments, and 
trophonematous filaments. In our opinion the name branchial 
filaments is most suited, as besides showing their origin, it does 
not suggest or imply anv function for these structures. As to 
their function Alcock considered them to be of use for the 
‘ tures in addition to having a probable secondary function of 
the absorption of yolk and the secretions of the maternal 
uterine wall, but it must be admitted that we are at present far 
from a proper understanding of the physiology of nutrition and 
respiration of these fishes 
It will be seen from what has been stated above that in 
the sabe ea — Speen: viviparous Elasmobranchs various 
peculiar devi adopted for the absorption of food during 
the life-history a a saudi individual. 
