62 W. A. HERDMAN. 



Fig. 20. — Part of another similar section, showing the narrow continuation 

 of the hepatic caicnm {h. c'.) sinking into the body and moving to a more 

 ventral position, so as to reach the median tube lying under the ovo-tcstis. 



Fig. 27. — Part of another section, showing the median tubular part of the 

 liver {m. I.) lying in the body below the ovo-testis (0. t.). S. \. 



Fig. 28, a, b, c. — The extremities of three cerata of Eolis (Facelina) 

 drummondi preserved in glycerine and then treated with potassic hydrate, 

 and slightly squeezed to show the long recurved tube connecting the tip of 

 the hepatic csecum with the cnidophorous sac. S. 1. 



PLATE X. 



Fig. 29. — Eolis (Galvina) picta from the left side. X G. 



Fig. 30.— Part of the tip of one of the cerata of Eolis (Facelina) 

 drummondi from Hilbre Island, preserved in glycerine and treated witli 

 potassic hydrate, showing the connecting tube {c. t.) between the cnidophorous 

 sac {01. s.) and the hepatic csecum {h. c). sph. Sphincter muscle, ec. Ecto- 

 derm, covered with fine cilia. /. m. and t. m. Longitudinal and transverse 

 muscle-bands. S. \. 



Fig. 31. — Transverse section near the tip of one of the cerata of Eolis 

 (Galvina) picta, showing the cnidophorous sac {en. s.) containing large 

 invaginated ectoderm-cells {ec'.), in which are placed the cnida. S. \. 



Fig. 32. — Longitudinal section through the tip of one of the cerata of 

 Eolis (Galvina) picta, showing the ectoderm {ec.) turning in at the 

 terminal aperture {ap.) to form the large cells or cnidocysts {ec'.) in the 

 cnidophorous sac {01. s.). S. \. 



Fig. 33. — Three of the cnida of Eolis (Galvina) picta. Z. -^. 



Fig. 34. — Transverse section (with freezing microtome) of one of the 

 cerata of Eolis (Acanthopsole) coronata from Puffin Island, ec. 

 Ectoderm, mes. Connective tissue and muscle-fibres, b. s. Blood-spaces in 

 the mesoderm, /i. c. Hepatic cascum. S. \. 



Fig. 35. — Transverse section of one of the cerata of Eolis (Cuthona) 

 nana (?), showing in addition to the hepatic csecum {h. c.) groups of large 

 gland-cells {gl.) embedded in the mesodermal tissues. S. \. 



Fig. 3G. — Longitudinal section through the tip of one of the cerata of 

 Eolis (Cuthona) nana (?), showing the opening (<•/;;.) of the cnidophorous 

 sac {ai. s.) to the exterior, the continuation iuwards of the ectoderm-cclls 

 {ec.) to form the cnidocysts (ec'.) which contain the cnida, the sphincter 

 muscle {sph.) round the opening of the cnidophorous sac into the hepatic 

 csecum, and the clumps of gland-cells {tjl.) lying in the mesodermal tissues. 

 S.i. 



