GARMAN: THE CHIMAEROIDS. 251 
The Claspers, Plate 3, Figures 1, 4, 5. 
The claspers of Rhinochimaera are similar in construction to those of Callo- 
rhynchus; they differ greatly from those of Chimaera. They have the ap- 
pearance of being formed of a narrow strip of cartilage rolled into a tube, then 
twisted so that the joined edges, indicated externally by a shallow groove, are 
given a complete turn in the length of each clasper. In the distal half each is 
round, hard, and slender; proximally each is much thickened by the strong 
muscles that surround its base and include the receptaculum, the opening to 
which is hardly visible on the outside. At the free end, the tube from the re- 
ceptaculum opens in the cleft extending from the interior of a small, fleshy, 
spine-covered bulb. As the claspers lie at rest, the clefts open outward from 
one another; but when in function the claspers are turned down and forward 
with a slight rolling motion, Plate 3, Figure 4, making the clefts to open 
inward, more toward one another, and the spine-covered surfaces to be carried 
outward so as not to come in contact. The spines at the extremities are erec- 
tile and hook toward the bases of the organs, thus forming effective holders. 
Turning the claspers down and forward from the body appears te open the 
mouths of the receptacula and bring them near the openings of the spermatic 
ducts. For comparison with those of Rhinochimaera the intromittent organs 
of a skate, Raia laevis, are figured on Plate 4, Figure 5; they are turned toward 
the head as in function, without indicating the peculiar structures of the carti- 
lages near the outer ends. The position of the clasper with regard to the ven- 
tral fin may be a matter of no great importance, vet it adds to the number of 
peculiarities distinguishing recent Chimaeroids from the Plagiostomes. The 
clasper of the Chimaeroid, Plate 3, Figures 1 and 2, occupies a position above 
the edge of the ventral fin, in a measure between the fin and the body ; that of 
the Plagiostome (Plate 3, Figure 3, 1 young specimen of Carcharinus terrae- 
novae) lies below the edge of the fin, which’extends between the clasper and 
the body. 
The Skull, Plate 1, Fig. 2. 
In the skull of Rhinochimaera pacifica there is little or no departure from 
the general type of Chimaeroid skull. The shapes as outlined, either from 
above, below, or from the side, may be described in similar terms, and the 
minor differences are not much greater than are to be seen in the different 
species of Chimaerae, or even than those obtaining in the different stages of 
an individual of a species of Callorhynchus. The parietal region is broader 
than that of Chimaera monstrosa, and narrower than that of Callorhynchus 
callorhynchus ; the frontal region is thicker, wider, and rounder, and does not 
form a blade-like crest as in Callorhynchus. The facial portion, oral and 
olfactory section, is more produced than that of Chimaera monstrosa; in this 
respect it more resembles that of Callorhynchus callorhynchus, in which the 
narial portion of the skull is much farther forward from the eye than in Chi- 
maera monstrosa, Plate 11. In the young of Callorhynchus callorhynchus, 
