399 
was found to be somewhat smaller in A. guttatus the general struc- 
ture of the two species was, on the whole, found to be very similar. 
Notwithstanding the fact that the specimen of A. y-graecum had been 
for several years in weak alcohol the tissues were found to be in a 
fairly good state of preservation. The specimen in questions was a 
female which measured about 33 cm in total length and weighed about 
500 grams. 
- The Electric Organ. 
The electric organ of A. y-graecum, on each side, may be said 
to be situated in the enlarged orbital cavity, the eye having been 
displaced forward and the skull widened to allow for its development. 
It is essentially rectangular in form, about 3 cm in length, 2 cm in 
width and 2 cm in depth, and tapers somewhat toward its cranial 
end where it is slightly notched to allow for the eyeball, which is 
situated at its craniolateral angle. The electric organ itself, which 
consists of some 200 parallel layers of electroplaxes arranged one 
layer on top of the other, is bounded above by the naked area of skin 
RAMUS 
OPHTHALMICUS 
OPHTHALMIC VEIN 
RECTUS EXT. _ 
2 
MAXILLARY N. ; H 
2 i N, OPTIC. II. 
Be i VEIN 
IYER] @ 
FACIAL V. Ava LPG el h 
> 1 ea RR - = 
a) Dealt Y) gi reerus INT. 
f 7 neu pauls Er 
Alan PERL _ pt —evecrarc N. 
La > i ij q | 
CILIARY N. f Lip came 4 
y I i IR ‘ ANAST, TRUNK 
VIER 
Y 65 zB. % FAN | 
MANDIB er 22 RN \ 
PaO IEULAR: N. En { iste 4 \ ~RECTUS INF, 
Se Tid a SSB 
ee. 
| ON 
LEV. ARC. PAL. | Fe OCULOMOTOR. 
iit 
OPHTHALMIC 
ART. CAROTID A, 
RSG ARG.” PAL RAMUS PALATINUS 
ADDUCTOR 
MANDIBULAE ELECTRIC N. 
Fig. 12. Transverse section through the middle of the electric organ of Astro- 
Scopus y-graecum, showing the relations of the nerves, vessels, muscles etc. Semi-dia- 
grammatic. Add. Arc. Pal. posterior end of anterior division of M. adductor arcus pala- 
tini; Anast. Trunk, anastomosing trunk between the right and the left ophthalmie 
arteries; Mucous Memb. mucous membrane of roof of mouth and pharynx ; Skin, naked 
area of skin on top of head. 3. 
OLFACTORY. L 
