L.M.B.C. TUilliELLAKIA. 59 



II.— KHABDOCCELIDA. 



A. ACCELA : — This group is of considerable interest 

 owing to the very simple organisation of its members. 

 They have no alimentary canal or digestive cavity. The 

 food (chiefly Entomostraca) is secured by the pharynx and 

 passed on to the parenchyma which is the assimilating- 

 tissue. An otolith is constantly present. 



Family — aphanostomid^. 



3. AiJhanostoma diversicolor, Oe. (PL XII, figs. 6 and 7.) 

 This species occurred in tide-pools close to the Port 



Erin Biological Station. It is distinguished by the 

 colouration of the anterior end. The central part is violet, 

 due to parenchymatous contractile pigment-cells ; the 

 peripheral portion and the extreme tip is coloured yellow 

 owing to yellow vacuoles in the parenchyma. This form 

 is recorded from Millport and Plymouth. 



4. Coiivoluta paradoxa, Oe. (PL XII, fig. 3.) 

 During July, swarms of this species in different stages 



of development occurred among drift sea- weed (especially 

 Geramia) in Port Erin Bay. Tide-pools also yielded speci- 

 mens but not so abundantly. The most interesting point 

 of its structure is the presence of brown bodies usually 

 known as yellow-cells or symbiotic algae, which live in its 

 tissue and largely determine its structure. 



It has been known for ten years (owing to the work of 

 Geddes and others) that another species of Gonvoluta 

 {C. schidtzii) contained chlorophyll, but whether the 

 chlorophyll isautochromic, that is a product of the animal's 

 activity ; or exochromic, and due to symbiotic unicellular 

 algse, is a question which can scarcely be considered as 

 thoroughly settled. 



Geddes' attention was first drawn to these Gonvoluta 

 when he saw what he took to be filamentous green sea- 



