PLATE I. 



n Acontia. 



h M'-si'iiti'rir filaments. 



c Stomata in the sopta, 

 c 1 Perioral stomata. 

 <• '- Marginal stomata. 

 eu Cuticle 



,/ Glandular streaks of the mesen- 

 teric filamenl 



« Ciliated streaks ol the mesenteric 

 filaments. 

 ■ h Ectoderm. 

 en Endoderm. 



g I! iproductive organs. 



h Septa, rh Directive septa. 



i * Iral disk. 



The lettering is the same in all the figures. 



k Wall. 

 I Pedal disk. 

 in Muscles. 

 vim. Mesodermal muscles. 

 ml Longitudinal muscles of the septa. 

 ml 1 Ketractor. 

 mp Parietobasilar muscle. 

 ml Transverse muscles. 

 iiir Radial muscles of the oral disk 

 and longitudinal muscles of the 

 tentacles 

 mt Circular muscle of the wall. 

 me Mesoderm. 

 n Urticating cells. 

 o Ovieells. 



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



iv. l. Oc. 2. 



a 1 6 10 



A 55 70 



C 95 125 



A with unscrewed front lens (uuscr. A) magnifies with Oc. 1 



;» Filaments] apparatus of the ovieells. 



p 1 Process of the ovicell. 



p' 2 Apical set of epithelial cells. 



r Marginal spherules. 

 rh Directive septa. 



s (Esophagus. 

 so Openings of the oesophagus into 



the radial chambers. 

 sr (Esophageal grooves. 



s; Lappets of the oesophagus. 



t Tentacles and the openings homolo- 

 gous with them. 

 I. ' Principal tentacles. 

 t 2 Accessory tentacles. 



v Openings of the pedal disk. 



The magnifying powers amount to 



All the figures are of natural size. 



Fig. 1. Porponia donga fa. 



Fig. 2. Porponia elongata, opened by 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 (A 1 ) reaching to the oesophagus, with mesenteric filament and acontia 

 but without reproductive organs ; then follow a pair of septa of the fourth order (A 4 ) and a pair of 

 septa of the third order (A 3 ). The right-hand portion begins with the next following pair of small septa 

 of the fourth order (A 4 ), and the much larger pair of septa of the second order (A-). 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 oesophagus 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 (t 1 ) belong to the pairs of septa of the first to the third order, 

 the two of the second row (C 2 ) to the pairs of septa of the fourth order, the four of the third row (t' i ) 

 to the interseptal spaces. 



Fig. 5. Cereus spinosus, 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 1 ) project with their coiled 

 mesenteric filaments below the lower margin of the cesophagus; the septa of the second order (A 3 ) 

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

 covered by the cesophagus ; the septa of the third order (A 3 ) project with their reproductive organs. 

 The septa of the fourth order (A, 4 ) are only visible at the side. 



Fig. 6. Pa metis excavctta, 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. Pliellia pectinata, 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 elegans. 



Fig. 9. Antholoba reticulata. 



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



