PLATE III. 

 THE EGG-CAPSULE OF CHIMERA COLLIEI SHOWN AT DIFFERENT STAGES OF DEVELOPMENT. 



( All figures about natural size.) 



Fig. 12. Capsule at the stage of the fertilization of the egg. The lowermost, i. e., valve-bearing, 

 end of the capsule is fairly complete, but its substance is delicate. The present capsule 

 collapsed during the process of removing it from the oviduct ; the egg it contained rup- 

 tured and flowed out through the unfinished end. 



Fig. 13. Capsule slightly older than the preceding. The opening end is of firmer consistency ; 

 the lateral web is well formed and somewhat pigmented. 



Fig. 14. Capsule slightly older than the preceding. The lateral dorsal webs are more perfectly 

 formed. 



Fig. 15. Capsule in which the tail-sheath is beginning to be formed. 



Fig. 16. Egg-capsule in which the egg-inclosing portion is nearly completed. The tail-sheath is 

 still a shapeless mass. The lateral webs are widest at this stage ; they later become 

 molded more closely and their delicate margins wear away soon after the egg is deposited. 

 Rugae are appearing near the posterior end of the capsule. An egg at this stage can be 

 incubated if a ligature is placed near the base of the caudal sheath. (In figs. 12 to 16 

 capsules are shown in dorsal aspect.) 



Fig. 17. Egg-capsule from which embryo has been naturally hatched. This is the most perfect of 

 the specimens which the writer dredged in Puget Sound. Its lateral webs are still 

 largely uninjured, the filamentous tip alone being defective lacking the bulbous organ of 

 attachment. The ventral aspect is here shown, and we note at d. h. the enlargement of the 

 wall of the capsule in which the mandibular region of the young fish comes to lie. The 

 figure shows also the close laminae in which the substance of the capsule is laid down. 



Fig. 17 a. Capsule of foregoing figure shown in lateral aspect. The valve of the capsule is repre- 

 sented as opened, a position assumed naturally only at the time of the escape of the young 

 fish, the valve and its springy mechanism reminding one of the "mouth" of the corolla of a 

 labiate plant. This figure shows the ridges, r. and /., which overlap (r. overlapping /.) 

 up to time the young fish escapes. It shows also how the neighboring tip of capsule 

 weathers, leaving only three eminences protruding, of which the one belonging to the lid of 

 the valve is the longest. The dorsal keel of the capsule is here well shown, d- k. It 

 varies little in height and passes nearly the whole length of capsule. 



Fig. 17 b. Capsule of foregoing specimen shown in dorsal aspect. This specimen shows adequately 

 the extent and character of the rugae of the lateral web. At its anterior end, at r. , appears 

 the rim of the valvular opening. In a capsule from which the fish has naturally escaped 

 this ridge no longer returns to its former position under the ridge /. 



Fig. 17 c. Capsule of foregoing specimen shown from in front. This figure was prepared to illus- 

 trate the character of the overfolded margins of opercular opening, and the peculiar curving 

 of the sides of valve. It shows also the prominence of the dorsal keel. 



(The capsule of fig. 17 is somewhat light colored for one which has been long deposited. Old capsules are usually 

 greenish black in color.) 



