Brotulids Killed by 1950 Eruption' — Gosline 
69 
Second, the organ is difficult to describe or 
illustrate adequately. In Figure 1, I have 
drawn the external features of the four Ha- 
waiian species for which I have males with 
a copulatory organ. 
Turner (1946: 92-96) has recently dealt in 
detail with the male copulatory apparatus of 
Dinematichthys, and I shall follow his termino- 
logy. In all the four species I have examined, 
the anus lies well forward on the midventral 
line of the copulatory chamber (Fig. \a, c) 
and is well separated from the anal origin by 
the copulatory apparatus itself. In Microbro- 
tula, a shallow-water genus described pre- 
Fig. 1. Male copulatory apparatus of four species 
of brotulids. h, Mkrobrotula rubra, from below and 
from the side; c, d, e, Diplacanthopoma (sp.?), from 
below, from the side, and from above; /, Diplacantho- 
poma {rivers- andersontl), from above; g, Cataetyx hawaii- 
ensis, from above. The head is to the right in all figures. 
Abbreviations: an, anus; cl, clasper; fl, reverted flap 
covering the urinary opening in Diplacanthopoma; fo, 
superficial fold of skin covering genital structures in 
Diplacanthopoma {rivers-andersonii)\ pe, penis; and ur, 
urinary opening. 
viously (Gosline, in press), the penis and 
claspers project posteriorly beyond the walls 
of the urogenital sinus and may be seen from 
below or from the side (Fig. \a, b). The penis 
is elongate and bent upward in the specimen 
at hand so that its tip lies in part between the 
claspers. The claspers are relatively large. 
In Cataetyx (Fig. Ig) and Diplacanthopoma 
(Fig. \c-f) the copulatory apparatus is bent 
upward and appressed against the midventral 
wall of the body in such a way that its outlets 
cannot be seen from below or from the side. 
In Diplacanthopoma rivers-andersoni? (Fig. if) 
much of the area of the urogenital openings 
is covered by a fold of skin. Such a fold is 
not now present in the other specimens. In 
both Diplacanthopoma and Cataetyx the area 
of the urogenital openings is divided into two 
sections. Within the posterior section lies the 
penis. Whether this organ is exserted (Fig. 
\e) or retracted (as apparently in D. rivers- 
andersoni?, Fig. if) seems to depend upon 
the circumstances at death and the nature of 
the preservation. The forward section is 
formed by the large opening of the urinary 
sinus, and the two sections are divided by a 
vertical wall which runs transversely. In Catae- 
tyx the urinary sinus opens directly to the 
exterior, but in Diplacanthopoma the urinary 
opening is entirely covered by a reverted flap 
which extends from the wall separating the 
two sections. In neither genus are any vertical, 
clasper-like flaps present. 
Though a far more complete knowledge of 
the variations in the copulatory apparatus 
with preservation must be gained before this 
structure, in the brotulids, can be used taxo- 
nomically with any confidence, it does seem 
that the copulatory organs of Mkrobrotula 
and Dinematichthys are of a rather different 
type from those of Cataetyx and Diplacan- 
thopoma. The male organs of these last two 
genera can in turn be separated readily by the 
presence of a reverted flap covering the urinary 
opening in Diplacanthopoma and the absence 
of such a flap in Cataetyx. 
The other character about which some com- 
