OF OECANTHUS AND TELEAS. 281 



Fig. 17. Transverse section through the cephalo-thorax posterior to the mouth opening. The salivary 

 glands are seen nearly cut off from the central band of mesoblastic and hypodermic elements. The nerve 

 cord is but slightly differentiated. X 250. 



Fig. IS. Lateral view of the germs of the sexual organs and the mesenteron. x 150. 



Fig. 19. Lateral view of the nervous system in the cephalo-thoracic region of the same stage, showing the 

 left half of the oesophageal commissure. X 150. 



Fig. 20. Fin organ of the same individual. X 500. 



Fig. 21. Dorsal view of the left half of the cephalo-thorax of the same individual. 



Fig. 22. Anal stylet of a female Oecanthus, showing the balloon-shaped organs on the inner surface of 

 its basal portion. X 125. 



Fig. 23. Three of these cuticular organs showing their parts. X 125. 



Fig. 24. A portion of the vagina. «, the large mucous glands. X 05. 



Fig. 25. A portion of the vagina] wall showing its muscles, a', b\ transverse and longitudinal fibres, ce. 

 the cells of the lining epithelium. X125. 



Fig. 26. An elder stein, the lower part of which is split open to show the relations of the eggs to th( 

 stem. Above are seen the rows of circular openings, which are the mouths of the egg pits. Natural size. 



Fig. 27. Section of the same, a, cap of wood and bark glued over the mouth of the pit to keep out 

 rain, etc. //, egg [§ : * uncovered, c, the position of the egg in the pit. X 5. 



Fie. 28. Side view of the cap. 



Fig. 2;). Theoretical section of the first abdominal segment, illustrating the formation of the gill pad. 

 X 20. 



Fig. 30. Transverse section passing through the external opening of the proctodaeum. X 50. The 

 genital armature is developed from the edges of the fold, g. a. 



Fig. 31. Lateral view of part of the head and thorax of an embryo just before the closure of the dorsal 

 wall. The plug of serosa cells (remnant of yolk sac) projects. 



Fig. 32. Camera outline of an embryo within the uninjured egg. The tail body is unusually large. X 25 



Fig. 33. Surface of the micropylar cap from which the outer cap has been removed. X 25. 



Fig. 34 Tip of the right half of the ovipositor of Oecanthus. X 50. 



MEMOIRS BOST. BOC. NAT. HIST. Vol.. III. 36 



