THE CTENOPHORA 



Order 4. Platyctenea. 



Ctenophora of creeping habit ; the body flattened in the principal axis 

 so that a dorsal can be distinguished from a ventral surface. No meridional 

 sub-costal canals, but a system of anastomosing peripheral vessels. Gestae, 

 when present, retractile within ectodermal pouches. Genera — Cterioplayia, 

 Korotneff, costae present ; Coeloplana, Kowalevsky, costae absent ; the 

 whole surface ciliated. 



SO 



ov. 



Fio. X. 



Ikroe Forskalii, Chun, from the sagittal aspect, m, month ; «, infundibulum ; so, sense 

 organ ; pf, papillifonn iirocesses of the polar fields ; sic, stonioda;al canal ; vtc, meridional 

 canals ; ov, ovaries ; sp, spennaries. The peripheral canal system is seen extending over the 

 entire surface. 



Sub-Class 2. Nuda. Tentacles absent. 



Order Beroidea, Lesson. 



Family Beroidae. Elongate, conical, or ovoid Ctenophora com- 

 pressed in the infundibular plane, with wide mouth and spacious stonio- 

 daeum. The otolith mass is uncovered, the polar fields surrounded by 



