PEOr. W. A. HERDMAN ON BRITISH TUNICATA. 44)9 



Greenland (' Yalorous ' Expedition) to examine, and I found 

 that they were the same as my own Norwegian forms. 



In regard to the supposed identity o£ Styela rustica, Linn., and 

 St. monoceros, Moller, I have the following remarks in my notes 

 made during the examination of my Norwegian collections : — 



These two closely allied forms are characteristically northern, 

 and We obtained immense numbers of them on July 11th when 

 dredging near the North Cape at depths of 75 to 150 fathoms. 

 They were of all sizes from little rounded ones like peas up to 

 cvlinders 5 cm. in length and 3 cm. in diameter. Many of them 

 were attached together in groups of a dozen or more, and most 

 of the larger ones had small ones growing on their tests. In 

 colour they varied from grey and pale yellow to rich orange 

 and brown. The edges of the siphons were generally o£ a 

 brilliant scarlet tint. Good coloured figures of both these forms 

 are given, by Wagner in his ' Wirbellosen Thiere des Weissea 

 Meeres.' Both Traustedt and Wagner, who have recently 

 written on these forms, consider that they are one species, and 

 that monoceros is merely rustica with a spine on the test ; but 

 after a careful examination of a large number of specimens of 

 both rustica and monoceros, I am of opinion that there are con- 

 stant characters in addition to the spine which can be relied 

 upon to distinguish the two forms, and that therefore they may 

 be regarded as distinct species. I have drawn up the following 

 descriptions from the North Cape specimens. 



StTELA RUSTICA (i.). (PI. XXXVI. fig. 1.) 



External appearance. Shape cylindrical to ovate, with the longer 

 axis antero-posterior, not compressed laterally ; attached by 

 the wide posterior end. Dorsal and ventral edges nearly straight. 

 Branchial aperture nearly or quite terminal ; atrial on the dorsal 

 edge, or slightly on the right side, nearly one third of the way 

 down : both square. Surface slightly roughened, especially at 

 the posterior end. Colour wheu alive pale yellow to dark red ; 

 in spirit dirty yellowish brown. 



Length 8-4 centim., breadth 1*5-2 centim. 



Test not specially thick, but tough and leathery ; whitish on 

 section and on the inner surface, where it is glistening — not 

 adhering very firmly to mantle. 



Mantle muscular and opaque. The external muscle-bands 

 run circularly and the internal longitudinally ; they do not 

 form a complete coating. Many endocarps projecting from the 



