A STUDY IN CAECINOLOGY. 77 
Plate 4. 
Fig. 1. Ventral view of Notopus doisipes, de Haan. The chelipeds have heen turned 
outwards and the pereiopods are extended to show their structure as far as 
possible. 
Fig. 2. Dorsal view of JVoiosce^ea cAimmorejs, nov. gen. et sp. The chelipeds and pereiopods 
have been extended as in fig. 1. 
Fig. 3. Ventral view of Notosceles chimmonis. 
Fig. 4. Ventral view of Lyreidus tridentatus, de Haau. Note the elongated digging dactyli 
of the first and second pereiopods. 
Fig. 5. Dorsal view of ifaniwoiV/es^ersoHaiKs, White MS., Henderson. The first and third 
pereiopods of the left .side are missing. 
Fig. 6. Ventral view of the same specimen as tig. 5. Note the large size of the sternal 
plastron, due to the great enlargement of sternum xii and the adaptation of the 
second and third pereiopods for swimming. 
Fig. 7. Left side view of Notopns dorsipes. The first three pairs of pereiopods have been 
pulled downwards to show the large extent of epimera xi and xii left uncovered 
by the edge of the branchiostegite. 
Fig. 8. Central nervous system of Sanina dentata. i. ocular, ii. antennular}', iil. antennary 
nerves; iv. mandibular nerves; v-ix. nerves to maxillae and maxillipeds issuing 
from the suboesophageal ganglion ; x. ganglion of cheliped ; xi-xiv. ganglia of 
the four posterior thoracic segments ; xv-xx. ganglia of the abbreviated 
abdominal nerve chain, st.d. aperture for passage of the sternal artery. 
Fig. 9. Right half of tlie endophragnial skeleton of Runiiia dentata as seen from within 
after division into two halves by a sagittal cut. The more anterior thoracic 
somites are omitted. The thoracic portion of the central nervous system is 
shown in situ. 'Note the great depth of the sagittal apodemes of sterna xii, xiii, 
and xiv. g. ll-<7. 14, the four posterior thoracic ganglia. 
Fig. 10. Central nervous system of Lyreidus tridentatus. Lettering as in fig. 8. 
Fig. 11.. A drawing from the left side of the eleventh and twelfth segments of the common 
lobster to show the relations of the endophragmal to the exoskeleton. xi and 
xii. sterna of the eleventh and twelfth segments. The preparation has been 
slightly tilted to the right to show the endopleurites edpl., consequently the 
epimera Ep. xi and Ep. xii are foreshortened. 
Fig. 12. A left side view of the thoracic skeleton ol Dromia vulgaris. The ventro-lateral 
projections of the sterna have been omitted, and the preparation is slightly tilted 
over to the right, xi-xiv. the four posterior thoracic sterna. 
Plate 5. 
Fig. 1-3. A posterior view of the thoracic skeleton of the common lobster, showing the large 
size of the penultimate and the structure of the last thoracic sternum. 
Fig. 14. A posterior view of the thoracic skeleton of Ranina dentata, illustrating the shape 
of the last three thoracic sterna and the formation of the sella turcica posterior. 
sg.a. sagittal apodemes. 
Fig. 15. A similar view of the thoracic skeleton of Dromia vulgaris. In the absence of 
sagittal apodemes in the posterior thoracic sterna the arthrophragms xiv/xv 
do not meet in the middle line, and there is no sella turcica. 
Fig. 16. The endophragmal skeleton of Notopus dursipes as seen from above after removal 
of the upper parts of the epimera. 6, 7, S, the articular cavities of the 
second maxilla and first and second maxillipeds. The endosternites edst. and 
endopleurites edpl. are clearly shown. 
