310 PROFESSOR W. A. HERDMAN ON THE 
of the species in my report upon the Tunicata of the Discovery Expedition.* The 
Discovery obtained in all five specimens from the east end of the Barrier and the 
neighbourhood of the winter quarters in M*Murdo Bay, in 10-20 fathoms. 
The more abundant material obtained by the Scotea gives us still further informa- 
tion in regard to the characteristics and variation of the species. Some of the Scotra 
Specimens, measuring up to 11 x 7x5 em., are the largest yet obtained; and some of 
them show a short peduncle at the place of attachment, a feature not previously 
observed. The characteristic spines on the test reach in some of these larger specimens 
toa length of 21 mm. and a breadth of about 1 mm. at the base. In some of these 
specimens the musculature of the mantle is remarkably strong, and consists externally of 
circular siphonal sphincters, beyond which is an oval sphincter, of numerous fibres, 
enclosing both siphons, while more internally radial muscles formed of exceedingly 
stout and strong fibres run outwards from the base of the siphons. Connective tissue 
permeated by fine fibres covers and unites all these various muscle bundles. 
Of the six folds on each side of the branchial sac, the largest is the one next to the 
dorsal lamina on each side, and the smallest is generally the third counting from the 
dorsal to the ventral edge. The transverse vessels are of four different sizes, and the 
stigmata are from nine to twelve in a mesh. One dorsal tubercle examined measured 
4°8 mm. from side to side and 3:2 mm. antero-posteriorly. 
The nerve ganglion is extraordinarily narrow and elongated, and may reach 9°5 mm. 
in length, with two nerves diverging from each end which can be traced with the eye 
round the sphincters of both siphons. The subneural gland is in the form of a thin 
layer over the ganglion. : 
A strong band of muscle fibres lies under the dorsal lamina and extends from the — 
mantle into the wall of the branchial sac near the posterior end of the nerve ganglion. 
Two of the specimens had Amphipods in the branchial sac. The specimens were 
obtained as follows :— 
I. Station 325,+ 9-10 fathoms, Scotia Bay, South Orkneys, July 1903. 
(1) 9x 6x6 em. (on a short peduncle). 
(2) 9°5 x 6°5 x 3 em. (very short peduncle). 
(B)583%5"5 x dvem: 
II. Station 325, 9-10 fathoms, June 1903; temp. 29° F. 
(1) 4x 4°5 x 2°5 em. (test only). 
(2) 8x 5°5 x 4 em. (with a smaller one attached). 
III. Station 325, 9-10 fathoms, August 1903; temp. 29° F. 
(1) 6x5x4°5 em. (also four empty tests). 
IV. Station 325, 9-10 fathoms, May 1903; temp. about 28° F. 
(1) 7°4.%:5.x.5.cm, 
(2) 6x 4x4 em. (also four empty tests). 
* Report National Antarctic Exped. : Nat. Hist., vol. v., “Tunicata,” London, 1910. 
+ The whole of Scotia Bay is termed Station 325 ; consequently, depths vary. 
