PLATE VI. 



The lettering is the same in all the figures. 



a Acontia. 



b Mesenteric filaments. 



c Stomata in the septa. 

 c ' Perioral stomata. 

 '- - Marginal stomata. 

 cu I 'uticle. 



d Glandular streaks of the mesen- 

 teric filaments. 



e Ciliated streaks of the mesenteric 

 filaments. 

 ek Ectoderm. 

 en Endoderm. 



3 Reproductive organs. 



h Septa, rh Directive septa. 



i Oral disk. 



k Wall. 

 I Pedal disk, 

 m Muscles. 

 mm Mesodermal muscles. 

 ml Longitudinal muscles of the septa. 

 ml 1 Retractor. 

 mp Parietobasilar muscle. 

 mt Transverse muscles. 

 mr Radial muscles of the oral disk 

 and longitudinal muscles of the 

 tentacles 

 ms Circular muscle of the wall. 

 me Mesoderm. 

 n Urticating cells. 

 o Ovicells. 



All statements given as to magnifying powers have reference to Zeiss's system. 



Oc. 1. Oc. 2. 



a 1 6 10 D 



A 55 70 F 



C 95 125 J 



A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times 



p Filfmental apparatus of the ovicells. 

 p 1 Process of the ovicell. 

 p 2 Apical set of epithelial cells. 



r Marginal spherules. 

 rh Directive septa. 



s Oesophagus. 

 so Openings of the oesophagus into 



the radial chambers. 

 sr (Esophageal grooves. 

 sz Lappets of the oesophagus. 



t Tentacles and the openings homolo- 

 gous with them. 

 t 1 Principal tentacles. 

 t 2 Accessory tentacles. 



v Openings of the pedal disk. 



The magnifying powers amount to 



Oc. 1. Oc. 2. 



.. 195 240 



.. 410 550 



.. 47o 580 



with Oc. 2 : 40 times. 



Transverse sections through different forms of the circular muscle. 



Circular muscle of Cereus spiTiosus. a 1 , Oc. 1. 



,, ,, Tealidium cingulatum. C, Oc. 2. 



,, ,, Polysiphonia tuberosa. a 1 , Oc. 2. 



,, ,, Tealia bunodiformis. C, Oc. 2. 



„ „ Phellia pcctinata. a 1 , Oc. 2. 



Comactisflagcllifem. C, Oc. 2. 



