ON SPLANCHNOTROPHUS. 59 
In the male Chondracanthus, too, the thorax and abdomen are nearly as well developed 
as in the new forms, only the segments are not so distinctly marked; and on the under 
side of the thorax, immediately behind the oral organs, there are two pairs of minute ap- 
pendages, each bearing a seta and a stout process, which are the homologues of the two 
pairs of thoracic feet, and go far to prove the intimate relation of the genera. The oral 
organs also in the two males are even more alike than they are in the females—the second 
pair of foot-jaws closely resembling each other, while in the latter they exhibit some 
disparity. 
Nicothoé likewise seems to be in some degree connected with our new form, though not 
by any means so intimately as is Chondracanthus. The lateral thoracic ovigerous ap- 
pendages in the female, and the aggregation of the external ova in sacs, are evidences of 
this connexion. But the complete segmentation of the body and limbs in both sexes 
seems to place this genus in close proximity to the Cyclopoidea, though the peculiar cha- 
racter of the oral organs shows its affinity to the Peecilopoda. 
EXPLANATION OF THE PLATES. 
PLATE XV. 
Fig. 1. Splanchnotrophus gracilis, femele ; ventral view, much enlarged: (a) thoracic feet; (b) lateral arm- 
like processes; (c) first abdominal segment, with portions of the ovigerous sacs attached. 
Fig. 2. Ventral view of the posterior portion of the body of the same, more highly magnified: (a) terminal 
extremity of the thorax, exhibiting the appearance of forming a distinct segment; (b) first ab- 
dominal segment, with remains of ovigerous sacs appended; (c) second or terminal segment, 
forming the bifid tail; (d) posterior pair of thoracic feet; (e) roots of posterior pair of lateral 
processes. : 
Fig. 3. Much-enlarged view of the oral organs of the same, as observed under slight compression : (a) first 
antenna; (b) second antenna; (c) labrum; (d) mandibles; (e) maxille; (f) first foot-jaws; (g) 
second foot-jaws. 
Fig. 4. View of the abdomen of the same, as seen in the compressor: (a) first segment ; (b) orifice for the 
passage of the eggs into the ovigerous sacs (c) ; (7) second segment ; (e) tail. 
Fig. 5. Anterior thoracic foot, much enlarged: (a) second member of the same. 
Fig. 6. Posterior thoracic foot: (a) second member. 
Fig. 7. Splanchnotrophus gracilis, male; enlarged lateral view: (a) first antennz ; (b) second antenna ; 
(c) thoracic feet; (d) first abdominal segment. 
Fig. 8. Ventral view of the same, exhibiting the antennae, oral organs, and thoracic feet. 
Fig. 9. Much-enlarged view of the oral organs of the same, seen by reflected light: (a) labrum ; (ò) 
mandibles; (c) maxille ; (d) first foot-jaws; (e) second foot-jaws. 
Fig. 10. One of the thoracic feet of the male, highly magnified. 
Fig. 11. Highly magnified view of the terminal tail-like segments of the body, seen by transmitted light : 
(a, a, a) the three posterior thoracic segments; (b, b) abdominal segments ; (c) tail; (d) seminal 
vesicles; (e, e) male intromittent organs. 
