DOESAL VIBKATILE FIN OF THE EOCKLING (MOTFFLA). 247 
literal myomeres. The walls of this groove more or less 
protect the rays, especially when these are depressed. While 
I find myself in essential agreement with the description and 
figures of the structure of this fin as given by Bogoljubsky 
(pp. 329-332, figs. 3-7), I must now proceed to important 
[loints, more especially in regard to the structure of the 
surrounding skin, which are not dealt with in his investiga- 
t ions. 
Fig. 2 illustrates the structure of the ventral part of the 
vibratile fin and adjoining parts, as seen in transverse sec- 
lions. The skin covering the groove in which the fin is 
situated is scaleless, and its detailed structure is of the greatest 
importance for the understanding of this organ. The skin 
consists firstly of a many-layered epidermis, consisting of a 
series of squamous cells externally, which gradually pass over 
into more columnar cells internally. Within the latter a 
deeply pigmented layer is situated. The epidermis also con- 
tains numerous mucous glands, and, of more importance, a 
large number of tactile nerve-endings and terminal or taste- 
buds. Beneath the epidermis there is a slight space traversed 
by strands of connective tissue, through which nerve-fibres 
}):iss. These strands of connective tissue pass internally into 
a well-defined layer of compact, ligamentous tissue. Under- 
neath the dermis the large lateral myomeres are situated. 
'I’he medial and ventral part of the section also contains a 
mass of connective tissue with two nerves on either side, the 
larsrer one beiny the ramus lateralis accessorius and the 
smaller one a dorso-spinal nerve. The section also passes 
through one of the depressor muscles. The medial and dorsal 
part of the section passes through the skin, which connects 
the basal part of the rays (the proximal parts of the rays not 
being included in the sectional plane). The epidermis of 
this fold of skin is similar in structure to that of the groove. 
Within the epidermis is a pigmented layer, and internally to 
the latter is loose connective tissue containing the horny fibres 
of the rays cut transversely, nerves, and blood-vessels. At the 
base of this fold of skin the head of the ray-carrier is seen. 
