EXPLANATION OF THE PLATE. 



Sibogita nauarchus, sp. nov. 



All figures are from unretouched photographs of specimens preserved in 

 formalin. 



Fig. 1. General side view of type. X 1.6. 



Fig. 2. Side view of manubrium of another specimen, to show the transversely 



folded gonads (go), limited to the interradii, and the blind terminations of the 



centripetal canals, c. ra, radial canal ; c. ira, interradial canal ; c. ara, adra- 



dial canal; 1., lip. X 3. 

 Fig. 3. Slightly more than one quadrant of the bell margin, with canals and 



tentacles, c. ra, radial canal ; c. ira, interradial canal ; c. ara, adradial canal. 



In the quadrant there are three young tentacles (t 2 ), in connection with which no 



canals have yet been developed. X 4. 

 Fig. 4. Aboral view of the apex of the bell in a specimen in which the manubrium 



has been dissected away, to show the blind terminations of the centripetal canals. 



Lettering as in Figs. 2 and 3. X 2 

 Fig. 5. Portion of margin, oral view, showing a young tentacle (t 2 ), in connection 



with which no canal has yet been developed. X 10. 

 Fig. 6. Similar view of a somewhat older tentacle (t 2 ), with a short centripetal 



canal, (c 2 ). T 1 , fully developed adradial tentacle. C 1 , adradial canal. X 5. 

 Fig. 7. An abnormality, in which two blind canals have been developed in con- 

 nection with a single tentacle (t 2 ). X 5. 

 Fig. 8. Terminal tentacular nematocyst knob, from fully developed tentacle. 



X 15. 



