1892.] NEW-YORK MICROSCOPICAL SOCIETY. 47 



green." L. ccendeiis is found in brackish waters, Z. produda is a 

 marine form. 



L. cceruleus possesses, moreover, a strongly defined median line 

 in each ot its lobes, but no such line is shown in Pritchard. 



No vent is mentioned by Wright in any of the species of the 

 genus, viz. : L. viridis, hyalina, atro-purpurea, a.r\d prodiicta j there 

 is one in cceruleus, by which excrement is voided, at the base of 

 the lobes, but it can only be seen when in action. 



Urnatella Walkerii sp. n. (PI. 29, Fig. 3). 



The polyzoun represented in Fig. 3 I have characterized as 

 Walkerii after my friend who was with me when it was captured. 

 It is a pretty and very polite form, very shy, and about the one- 

 thirtieth of an inch in length when extended. Its politeness- 

 consists in very frequently bowing body and stem from its base, 

 and then returning to an erect position. 



It is almost identical with U. gracilis Leidy, save that gracilis 

 has several constrictions in the stem, whilst Walkerii has the stem 

 perfectly plain and somewhat tapering. Leidy says of Z. gracilisr 

 " The longest stems consist of a dozen joints, and measure about 



Explanation of Plate 31. (After Allman.) 



Cordylophora lacustris. Fig. 4. Portion of the walls of the stomach highly magni- 

 fied a. Ectoderm, its cells containing thread-cells. 6. Endoderm composed of elon- 

 gated cells, with true secreting cells in their interior, c. Secreting cells with evident 

 nucleus, d. Secreting cells with nucleus obscured, e. Granular mass. /. Muscles.— 

 Fig. 5. Thread-cells before e.x:sertion of filament.— Fig. 6. Thread-cells after exsertion 

 of filament.— Fig. 7. Cells liberated under pressure from the ectoderm, some with a 

 thread-cell, others with a nucleus —Fig. y. Cells liberated by pressure from endoderm 

 of stomach.— Fig. 9. Portion of tentacle near its root. a. Ectoderm with thread-ceils. 

 b. Endoderm. c. Muscular fibres. -Fig. 10. Cells containing secondary cells from endo- 

 derm.— In Figs. 11-14 the letters indicate : o. Diverticulum from the coenosarc. h. Exter- 

 nal investment of the reproductive capsule, c. Cellular sac. d. Ramified canals, 

 e. Structureless sac secreted outside of the cellular sac— Fig. 11. Reproductive capsule, 

 very early stage.— Fig. 13. The same, more advanced.— Fig. 13. Ideal longitudinal sec- 

 tion of the same at the same stage.— Fig. 14. The capsule more advanced the ova 

 being visible.— Fig. 1.5. The same still further advanced, the ova lying on the extremity 

 of the diverticulum.— J'iG. 16. More magnified view of ovum, segmentation into a mul- 

 berry-like mass.— Fig. 17. Capsule still further advanced, ova elongated.— Fig. 18. The 

 same, ova swarming in interior.— F'ig. 19. The same, sac ruptured, ova escaping as free 

 ciliated infusoria.— Fig 80. Embryo just after escape.— Fig. 21. The same, assuming 

 pyriform figure.— Fig. 22. The same after locomotive stage, fixed by one extremity.. 

 Fig. 23. Further development, tentacula budding, stem surrounded by a delicate poly- 

 pary.— Fig. 24. Male capsule, a. Contents escaping under slight pressure, b. Caudate 

 cells Hberated from capsule, c. Spermatozoa. 



