TETHYS-EUROPEAN. 69 



I. Species of European Seas. 



a. Swimming lobes united behind as far up as the excurrent siphon ; 

 mantle having a wide median orifice exposing the shell, its 

 edges not thickened. A group of unicellular glands each with 

 independent duct in place of the opaline gland 



depilans, punctata. 



act. Swimming lobes free to their union with the foot behind ; man- 

 tle having a median minute perforation or a little tube. 

 b. Opaline gland with multiple ducts ; green ; length 27 cm. 



lobiancoi 

 bb. Opaline gland grape-bunch like, with one duct. 



c. Length 12-20 cm. ; very dark, sometimes flecked with 

 light leporina 



cc. Length 6 cm. ; obscure green, marbled with black 



marmorata 

 ccc. Pale yellowish with scattered black rings dactylomela 



T. DEPILANS Linne. PI. 23, figs. 26, 27 ; pi. 24 ; pi. 33, fig. 25. 



Length about 20 cm. Shorter and more compressed than T. lep- 

 orina. Swimming lobes united behind as far forward as the mantle 

 siphon ; foot rounded posteriorly. Mantle or gill-cover with a 

 broad round orifice leading into the shell-cavity, and surrounded by 

 dark brown rays. On the under side of mantle edge the numerous 

 glands secreting a milky fluid (homologous with the purple glands 

 of T. leporina) open. Siphon of the mantle shorter than in lepo- 

 rina ; genital and anal openings as in leporina. Behind the genital 

 opening there are numerous one-celled glands each with its separate 

 opening, in place of the grape-bunch like gland of leporina (pi. 33, 

 fig. 25). 



Color extremely variable ; generally the ground is light brown, 

 often gray-brown, rarely quite dark, always with white or light 

 gray spots with irregular outlines. Shell similar to that of leporina 

 but with stronger calcareous layer. 



Mediterranean and Adriatic Seas; Atlantic: Torbay, S. coast 

 Devon, England, and Channel Is. ; W. coast of France, Madeira, 

 (? and Cape of Good Hope). 



Laplysia depilans L., Syst. Nat., 12, p. 1082, founded mainly on 

 Lernea of Bohadsch, de quibusdam animalius marinis, etc., pi. 1-3. 

 BARBUT, The Gen. Vermium, p. 31, pi. 3, f. 5, 6. BRUG., Encycl. 

 Meth., pi. 83, 84 (copied from Bohadsch). LAM., An. s. Vert., PEN- 



