THE ANATOMY OF AN AUSTRALIAN LAND PLANARIAN. 51 
So far as | am aware, no Australian land Planarian has hitherto been anatomically 
investigated, although Professor Moseley (1) and Messrs. Fletcher and Hamilton (2) 
have described the external characters of a number of species. Moseley, in the work 
referred to, observes: ‘‘I have been able to find no published description of these 
forms, for the reception of which I have made the new genus Cenoplana 5 
Their anatomy I have not yet worked out, but a few transverse sections made show 
that they closely resemble Rhynchodemus in the structure of their lateral organs, whilst 
in the arrangement of their muscles they are intermediate between Geopflana and 
Dolichoplana, from which latter they differ principally in having many small eye-spots 
instead of a single pair of larger eyes.” The genus Cenoplanais defined as follows :— 
“Body long and worm-like, much rounded on the back, flattened on the under 
surface, without an ambulacral line. External longitudinal muscular bundles largely 
and evenly developed over both dorsal and ventral regions. Lateral organs* distinct 
and isolated asin Rhynchodemus, and, as in it, connected by a transverse commissure 
Eyes absent from the front of the anterior extremity, but present in two lateral 
elongate crowded patches placed just behind the anterior extremity and scattered 
sparsely on the lateral margins of the body for its entire extent. Mouth nearly 
central, pharynx cylindrical.” 
Messrs. Fletcher and Hamilton (2) ably criticise the new genus. “If our 
supposition be correct that Professor Moseley from the examination of indifferent 
spirit material overlooked the presence of eyes on the anterior extremity of the 
Australian land Planarians examined by him, it seems unnecessary, in the present 
state of our knowledge, to separate these forms as a distinct genus Cwnoplana on 
purely anatomical grounds (the arrangement of the muscles, and of the lateral organs). 
No doubt eventually it will be found necessary to take anatomical characters into 
account in defining the genera, and in establishing his two new genera Cenoplana 
and Dolichoplana Mr. Moseley did so. But we cannot find such definitions of 
Geoplana and Rhynchodemus . . . . Under these circumstances, therefore, and 
as all the many-eyed Australian species we have met with may be referred to the 
genus Geoplana as at present defined, we venture to express the opinion that the 
retention of Cenoplana is unnecessary.” 
These remarks are very much to the point, and I can heartily endorse them. So 
far as I am aware, only one species of Geoplana has been anatomically described, viz., 
Geoplana traversu, from New Zealand (1) and the description of that species is by no 
means complete. 
At present, therefore, I consider that we are justified in distinguishing only two 
genera of Australian land Planarians, viz., Geoplana, with many eyes, and 
Rhynchodemus, with only two eyes.+ That these two genera will subsequently 
* Longitudinal nerve cords. A. D. 
+ I would here refer the reader to my subsequent observations on the eyes of land Planarians, in the present paper. 
