CHROMODORIS ZEBRA HEILPRIN: A DISTINCT 



SPECIES 



W. M. SMALLWOOD and ELIZABETH G. CLARK 



Contributions from the Bermuda Biological Station for Research No. 26, and from 

 the Zoological Laboratory of Syracuse University 



SIX FIGURES 



The following paper supplements one published by the senior 

 author (Smallwood, '10). The two papers present the general 

 morphology of Chromodoris zebra and point out the characters 

 which distinguish it from C. villafranca. Bergh ('92) believed 

 the two to be identical. The first paper gave a description of 

 the external anatomy of C. zebra — the present one, the internal 

 anatomy of the species. While our study of the internal anatomy 

 has shown no marked deviation from the general plan of organi- 

 zation of the Doridae,^ — so well described by Eliot ('10,pp.36to49) 

 with Doris tuberculata as example, — it has furnished information 

 concerning the anatomical details of this species not hitherto 

 published. 



DIGESTIVE SYSTEM 



The mouth leads into a short but rather wide atrial chamber 

 (6 mm. long by 9 mm. in diameter), the inner wall of which is 

 lamellated. At the posterior end of this chamber a ring-shaped 

 depression forms the boundary between the lateral wall and the 

 posterior wall, the latter constituting the labial disc. A vertical 

 slit-like opening in this disc is the entrance to a passage extending 

 posteriorly for 4 mm. ; this passage is lined with closely set spines, 

 which form what is sometimes incorrectly termed a 'prehensile 

 collar.' This spinous passage expands at its posterior end into 

 the main buccal cavity, 5 mm. in length by 6 mm. in diameter. 

 The floor of the main buccal cavity is formed by the odontophore, 

 a round muscular prominence bearing the radula and divided into 



625 



