OLIGOTRKMA PSAMMITES. 233 



Olilgotrema psammites: a New Ascidian 

 belonging to the Family Molgulidse. 



Oilbcit C. Botii'iic, D.Sc, F-L,.*., 



Fellow and Tutor of New College, Oxford ; University Lecturer in 



Comparative Anatomy. 



With Plates 19—23. 



The interesting little Ascidian wliich forms the subject 

 of this paper was dredged by Dr. A. Willey from a depth 

 of fifty fathoms off Lifu, New Britain, and was sent to 

 me among a collection of Zoanthids made in the same 

 locality. Externally the animal has so little resemblance to 

 an Ascidiau, and has so many features resembling those of 

 Anthozoa, that it miofht well be mistaken for a member of 

 the latter group. The body is sack-shaped and covered with 

 grains of sand, like that of a Zoantbid. The mouth, or more 

 correctly, the branchial aperture, is transversely elongated 

 and bordered by tumid lips (Fig. 2), and there is a circlet of 

 six pinnate arms or tentacles resembling those of an 

 Alcyonarian surrounding the mouth. The internal organs 

 can only be distinguished as a dark mass through the trans- 

 lucent walls of the body, and the atrial siphon is so small 

 and inconspicuous that it might easily escape observation. 

 My attention was at once atti-acted by the presence of six 

 piunate tentacles, and, suspecting that the animal was new to 

 science, I cleared it for preliminary examination in dilute 



