SKATES' EGGS AND YOUNG. 623 
object of it is not apparent, unless it be to assist in securing an anchor- 
age, n the entanglement of its filaments with submarine plants or rough 
surface 
In à sas instance, in the dissection of skates, an imperfect egg-case 
was found in each oviduct, the development of it having just begun, 
The hinder horns and the hinder edge of the capsule were the only parts 
ompl - They were contained in the glandular portion of the oviduct, 
which is quite thick during the re- 
productive season, and is mostly 
made up of very minute and slender 
follicles, of great length. From some 
of them fibrils Hemde, identical 
in structure with those out of which 
the cases are made, and which, after 
being liberated, are doubtless 
moulded into the shape 
cases, and cemented together by 
some secretion from -the oviduct. d 
The horns are formed in grooves on with de feli [quo eer ren d 
either side of the duct, and the ^4 ECT MAE senteric artery; c, dorsal 
pouch for the yelk in the intervening 
Space. A careful examination of the üry and oviduct in the above in- 
stance showed the singular fact, tk MER some of the yelks were 
mature, none had as yet been detached from the ovisacs. This circum- 
Stance renders it probable, that, after the horny pouch is partially formed, 
the yelk descends and enters it, and that then the other portions are 
completed. If this supposition, based upon a single observed instance, 
were to be confirmed by further examinations, it would prove the exist- 
f an interesting deviation from a rule 
among animals aude: supposed to be 
without exception, viz. : t the presence of 
the yelk in the rl is necessary before 
the formation of the egg-coverings can 
b 
Fig. 86. € 
un 
@ 
Au 

a Fig. 87. 
gin. 
f the cases which we have ex- 
amined have we found the foetus surrounded 
either by a membrane or by albuminous 
i matter, but in every instance the yelk and 
Under side of the yelk of fig.83, the embryo were fully exposed to contact 
Rent cack tet ee ie the water, which entered by the open- 
with’ the triangular terminal ings already described. An albuminous 
overing may have existed at an earlier 
— and have been Mesi 
Yelk.—After the body of the embryo has become well defined. it is at- 
tached to the yelk by a slender umbilical cord about half an inch in length 
g. 86). The yelk has not the pyriform shape so common in other 

