TRIOPA CLAVIGER. 



The skin is densely filled with spicula, which are of various forms ; generally forked or 

 triradiate, occasionally straight, and a few cruciform or dagger-shaped. The latter are mostly 

 found in the branchiae, and those of the first description are most developed in the lateral 

 processes. 



Dr. Johnston was the first to notice this handsome species as a native of Britain, and 

 it has since been found to be pretty generally diffused. It varies a little in appearance, which 

 has induced some naturalists to think that more than one species might be included in it. but 

 no good distinguishing characters have yet been pointed out. The four branchial plumes 

 described and figured by Miiller, are so unlike the usual appearance of those organs in the 

 Dorididre that it is fair to conclude they have been misunderstood. The specimens found 

 on the Northumberland coast are much smaller, and have the branchiae much less developed 

 than those from the south of England ; the appendages of the cloak, too, are more clavate, and 

 the orange colour does not extend so far down them. This form is probably the T. jmlcher 

 of Johnston, which is stated to have tubercular branchiae ; a mistake arising from the 

 difficulty of observing them, on account of their minuteness and transparency. 



Figs. 1, 2, 3. Triopa claviger, different views. 



4, 5. Front and side views of a tentacle. 



6. One of the frontal appendages much magnified, 



7. Spicula. 



