PLATE I. 



The lottcrin" is the same in all the fiKures. 



n Acontia. 



b Mesenteric filaments. 



c Stomata in the scptiL 

 c ' Perioral stomata. 

 c- Marginal stomata. 

 CK Cuticle. 



a! Glandular streak.s of the mesen- 

 teric filaments. 



e Ciliated streaks ol the mesenteric 

 lii:iments. 

 ck Ectoderm. 

 en Kndoderm. 



7 1!. 'productive organs. 



h Srpta. rh Directive septa. 



i Oral disk. 



k Wall. 

 I Pe.lal disk. 

 m Mu.s(dcs. 

 mm Mesodermal muscles. 

 ml Longitudinal muscles of the septa. 

 ml^ Retractor. 

 7)ip Parietobasilar muscle. 

 mt Transverse muscles. 

 mr Radial muscles of the oral disk 

 and longitudinal muscles of the 

 tentacles 

 7n« Circular muscle of the wall. 

 me Mc'siulerm. 

 n Urticatiug cells. 

 Ovicells. 



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



Oc. 1. Oc. 2. I 



a' : 6 10 D 



A 55 70 F 



C 95 125 I J 



;) Filamental apparatus of the ovicell.s. 

 2' ' Process of the ovicell. 

 p'^ Apical set of epithelial cells. 



r Marginal spherules. 

 rk Directive septa. 



s (Esophagus. 

 so Openings of the oesophagus into 



the radial chambers. 

 sr Qisophageal grooves, 

 s: Lappets of the (esophagus. 



t Tentacles and the openings homolo- 

 gous with them. 

 t^ Principal tentacles. 

 f Accessory tentacles. 



V Openings of the pedal disk. 



The magnifying powers amount to 



Oc. 1. Oc. 2. 



... 195 240 



.. 410 550 



.. 470 580 



A with unscrewed front lens (unser. A) m.ignifies with Oc. 1 : 30 times; with Oc. 2 : 40 times. 



All the figures are of natural size. 



Fig. 1. Porponia elongafa. 



Fig. 2. Porponia elongata, opened liy a longitudinal incision ; and the pedal disk split up by 

 repeated radial incisions. In the lettering on the plate for so read sr. 



Fig. 3. Cereus spinosus. 



Fig. 4. Cereus spinosus; the half of a sextant prepared by cutting into separate pieces; in the left-hand 

 portion one of the principal septa (/< ' ) reaching to the oesophagus, with mesenteric filament and acontia 

 but without reproductive organs ; then follow a pair of septa of the fourth order (h*) and a pair of 

 septa of the third order (h^). The right-hand portion begins with the next following pair of small septa 

 of the fourth order (h*), and the much larger pair of septa of the second order {h"^). All the accessory 

 septa have mesenteric filaments, acontia and reproductive organs, but do not reach the CESophagus 

 which hangs over them like an apron. A portion of the esophagus has been removed in the left-hand 

 portion. Only the septa of the second order have coiled mesenteric filaments like the principal 

 septa. The three tentacles of the first row (fl) belong to the pairs of septa of the first to the third order, 

 the two of the second row (/-) to the pairs of septa of the fourth order, the four of the third row (P) 

 to the interseptal spaces. 



Fig. 5. Cereus s2J>nosus, opened by a longitudinal incision, which has run between a septum of the 

 third and a septum of the fourth order. The principal septa (A^) project with their coiled 

 mesenteric filaments below the lower margin of the oesophagus ; the septa of the second order (h^) 

 project with smooth edges as their coiled mesenteric filaments, and their reproductive organs are 

 covered by the cesophagus ; the septa of the third order (h^) project with their reproductive organs. 

 The septa of the fourth order (h*) are only visible at the side. 



Fig. 6. Paractis excavata, one-third of the animal has been cut out in order to show the arrangement 

 of the oral disk and the corona of tentacles ; the section is directed so as to show two principal septa. 



Fig. 7. PheUia pcctinata, opened longitudinally ; the section runs between two principal septa of 

 the same pair ; the principal septa project with their coiled mesenteric filaments below the oesophagus. 



Fig. 8. Antheomorphe elegciTis. 



Fig. 9. Antlwloha reticulata. 



Fig. 10. Porponia robusta ; fig. 10, «, a separate tentacle. 



