42 JAMES Francis ABBOTT, 
The following account deals with the details of structure and 
homologies of “Coeloplana”, a form hitherto known only from a 
superficial description of a single specimen. The material for the 
present paper was described in a preliminary note in: Annotationes 
Zoologicae Japonenses, Vol. 4, 1902, but press of other duties has 
made it impossible to complete the work until now. 
A. Historical. 
1. Kowatevsky’s Coeloplana. 
.In 1881, KowazEevsky discovered in the Red Sea near the city 
of Tor, a form to which he gave the generic name Coeloplana*), in 
allusion to the apparent combination of Coelenterate and Planarian 
characters which it afforded. Kowatrvsxky’s report was published 
in the proceedings of the Zoological Section of the Sixth “Convention 
of Russian Naturalists and Physicians”.*) It was reviewed in the 
“Zoologischer Anzeiger”, and our knowledge hitherto has depended 
upon this latter rather brief account. The Russian naturalist 
described his single specimen as grayish above and white ventrally, 
round in outline and measuring about three lines in one direction 
by two lines in the other. It was found on Zostera at a depth of 
10 to 15 fathoms and was mistaken for a planarian until his 
attention was attracted by the extrusion of the tentacles. The 
abstract in the Zoologischer Anzeiger describes Coeloplana as ciliated 
all over and Kowatevsky’s figure shows cilia all about the periphery 
but he makes no such statement in the original paper. The animal 
was described as “Planarian-like”. There was a median ventral mouth 
leading directly into a central gastric cavity from which branching 
canals ramified. Four main divisions led off from the central cavity 
and divided up into many subdivisions, separated by trabeculae 
connecting the upper and lower body walls. These canals according 
to KowaLEvsky opened into a circum-peripheral canal from which 
extended blind processes. Above the mouth was a Ctenophor-like 
1) According to the strict rules of nomenclature the spelling “ Coele- 
plana’ should be retained, but as the spelling “Coeloplana” has been 
used constantly since KOWALEVSKY’s paper and for orthographic reasons 
is so very much to be preferred, it has seemed best to continue its use 
in the present paper. 
2) Uster. o6m. 1106, ecrecrso3, Vol. 43. Tpyar. 300.1. orgbaa. Vol. 1. 
