416 GILMAN A. DREW 
GR, gland ridge; typhlosole-like in appearance. Under one edge of this ridge 
is the groove along which the forming spermatophores are passed. 
HC, hyaline core. Present in forming spermatophores, but later disappears, 
probably by liquefication, possibly by withdrawal to the cement body. 
HG, hardening gland. This may not be properly named. Only the aboral end 
of the spermatophore is thrust into this gland. In this position the aboral 
end of the spermatophore is always covered by the outer tunic, which is 
smooth elastic, and not sticky. The hardening of the oral end of the sper- 
matophore takes place in the finishing gland, possibly by secretions deliv- 
ered with the spermatophore from the hardening gland, possibly by secretions 
furnished by the finishing gland itself. 
IM, inner membrane. A membrane of the ejaculatory apparatus and a cover- 
ing for at least a portion of the cement body. On its inner surface it bears 
the spiral filament. It is so thin it has been represented by a line. 
IT, inner tunic. Inconspicuous and represented by a line over the sperm mass 
and connecting cylinder, becoming thicker and more conspicuous over the 
ejaculatory apparatus, where, with the outer membrane, a double membrane 
is formed. This becomes part of the covering of the sperm reservoir when 
this is discharged from the spermatophore. 
MM, middle membrane. A conspicuous membrane of the ejaculatory appara- 
tus. The tube formed by it is firmly attached to the outer tunic at the 
oral end and has its open mouth applied to the shoulder of the cement body 
beneath the outer membrane. 
MM‘, middle membrane, cap end. This nation ruptures when ejaculation of 
the spermatophore begins. 
MT, middle tunic. Probably of a highly osmotic material that furnishes part 
of the power which causes ejaculation of the spermatophore. 
MTG, middle tunic gland. 
MG‘, mucilaginous gland, part one. 
MG?, mucilaginous gland, part two. The separate functions of these two parts 
have not been determined, but together they form the secretions with which 
the spermatozoa are mixed, and which form the,connecting cylinder, the 
hyaline core, and the cement body. 
OM, outer membrane. A portion of the ejaculatory apparatus. For most of 
its length it is intimately associated with the inner tunic so the two appear 
as a double membrane. The tube which it forms is applied to the middle 
membrane and ends with a free opening near the oral end of the spermato- 
phore. With the inner tunic it forms the sperm reservoir. 
OT, outer tunic. A highly elastic tough outer covering. This, together with 
the middle tunic, furnishes the power that causes ejaculation. When the 
spermatophore nears completion this tunic shrinks until it is under great 
tension and the spermatophore becomes very turgid as the result. 
OTG, outer tunic gland. It is possible this may not be responsible for the for- 
mation of the outer tunic, but it probably is. 
PA, point where adhesion betwee: the middle and inner membranes covering 
the cement body becomes strong. Form this point to the end of the middle 
membrane they adhere firmly. As the spermatophore nears completion, 
the point of adhesion is not so easily seen, but during ejaculation the adhesion 
is seen to be strong. 
