MORPHOLOGY OF CYCLOPS. 15 



Fig. G. Right anterior maxilliped, posterointernal face, showing renal aperture. 



Fig. 7. Right posterior maxilliped, same face. 



Fig. 8. Left 1st thoracic limb, posterior face; muscles of anterior side omitted. 



Fig. 9. Right 4th thoracic limb, anterior face ; muscles of posterior side of protopodite omitted ; pore- 

 canals and (in exopodite lower joints) outlines of hypoderm cells indicated. 



Fig. 10. Section through the right coxopodite and coupler of a thoracic limb; from a horizontal section. 



Fig. 11. Free apex of labrum. x 375 : E. 



Fig. 12. Mouth of a live animal, from below, showing labrum, with salivary pore, preoral bar, para- 

 gnathse (the right, pff.r.) turned out, and exposing its internal face. 



Fig. 13. Paragnathse, seen dissected out in ammonia, seen from above (oral aspect). 



Fig. 14. Part of the sternal region of ccphalon, ammonia preparation, showing inner and outer and inner 

 arthrodial ridges, sockets, and shrivelled remains of kidney. 



Fig. 15. Free entosternite, dorsal view, from a horizontal section ; the lined parts are the retractor 

 muscles attached to the postmaxillary apodeme, and the squarish dots are the origin of the 

 retractors of the preoral bar seen by transparency, x 125 : D. 



Plate II. 



Fig. 1. Adult female, seen from above; the reproductive organs and extrinsic muscles of the intestine 

 and anus put in diagrammatically, as if the animal were transparent. x 48 : 1". 



Fig. 2. Adult male; reproductive organs diagrammatic, x 48 : 1". 



Fig. 3. Sternal region of anterior part of thorax (compiled from two sketches of the live animal) : the 1st 

 limb and coupler are seen turned back ; the region of the 2nd thoracic segment is exposed by 

 the 2nd limb (not shown) being turned forward, and the 3rd limb turned back. Part of 

 the ventral nerve-cord shows by transparency, and the transverse direction of the nerve to the 

 1st limb, as compared with the obliquity of those to the 3rd and 4th, is obvious. The front 

 of the nerve-cord is too narrrow. x .150 : D. 



Fig. 4 a. Sternal region at junction of fore and hind body (4th to 6th segments) of immature female 

 before last moult, diagrammatized from life, showing 5th thoracic limb ; great flexors of body 

 and median apodeme of their insertion, nerve-cord enlarged at hinder end of 4th and 5th seg- 

 ments, and bifurcating in the 6th, giving off at the former enlargement nerves to the flexors, 

 to the 5th limb, and to the sides of the 6th segment, and at the latter nerves to the vulva and 

 to the sixth limb (genital limb), x 150 : C and D. 



Fig. 5. Same region of adult male, showing in addition the genital valves, vesiculse seminales, left 

 vas deferens, and the nerve from the 4th segment to the side of the 6th. x 150 : C and D. 



Fig. 6. Side view of same region of female combined from life and sagittal sections, showing vulva, sperma- 

 theca, and pore, 6th limb (genital valve), and terminations of pleural nerve, x 150 : C and D. 



Fig. 7. Frontal section (from a transverse series) showing corneal facets, &c. x 250 : D. 



Fig. 8. Horizontal section through eye and front of brain, showing left optic nerve, and (at a slightly 

 higher level) right inferior frontal nerve, x 125 : J. 



Plate III. 



Fig. 1. Sagittal section of adult female (nearly median), showing chief organs in situ; histologica details 

 diagrammatic ; ganglion of fourth thoracic segment [g. th. 4) too large, x 48 : 1". 



Fig. 2. Sagittal section through last three segments of abdomen, showing epithelial valve at junction of 

 intestine and rectum, median (dorsal) muscles of rectum, and ventral apertor ani, and continu- 

 ation of one fork of nerve-cord to furca. x 250 : D. 



Fig. 3. Intestine, from above (horizontal section, osmic acid and cochineal), showing the epithelium and 

 SECOND SERIES. — ZOOLOGY, VOL. V. ? 



