8 W. A. HERDMAN. 
numerous on the folds than in the interspaces (fig. 5). On the third fold, for example, 
there are about twenty-three on the fold and seven in the adjoining interspace. In 
another case, however, there were ten on a fold and five in the interspace. Transverse 
vessels are of four sizes, of which the three larger sizes (fig. 6, tr, tr’, tr”) are arranged 
with regularity (1—3—2—3—1, etc.), and the fourth or smallest size occur irregularly 
and may be as numerous as four or five between any two of the others. The meshes 
are elongated horizontally and contain nine to twelve stigmata. The stigmata are 
rather long and straight, and usually narrower than the interstigmatic vessels (fig. 6). 
Dorsal Lamina represented by a series of languets, which are smaller and very 
closely placed anteriorly, and are further apart and larger posteriorly (fig. 4, d. /). 
Tentacles about sixteen, large, of two orders, alternating with a third order of 
much smaller ones, so: 1—3—2—8—1l. 
Dorsal Tubercle very large, about 3 x 5 mm., horseshoe-shaped, opening anterior, 
horns turned inwards and coiled (fig. 4). Peri-tubercular area very wide. 
Nerve-ganglion long and narrow, may be over 9 mm. in length, giving off two 
nerves at each end, which can be traced some way round the sphincters. 
Alimentary Canal forming a very long straight loop. sophageal opening 
large, crescentic, with corrugated lips. Stomach having the wall folded into thin 
lamelle projecting into the lumen. Anus with laminated edge, attached to the mantle 
exactly alongside of cesophagus. 
Gonads an elongated compact mass on each side of body, with papillary openings 
into the atrial cavity. The left gonad entirely fills the intestinal loop. 
This species, which would doubtless fall into the genus Pyura in the nomenclature 
of MM. Hartmeyer and Michaelsen, was first described by Prof. Sluiter in 1905,* and 
more fully in 1906, in his report on the Tunicata of Dr. Jean Charcot’s Antarctic 
expedition of 1903-05. That expedition obtained two specimens of this species at 
“Tle Booth Wandel, 40 métres”; but the figure of the exterior (Expéd. Charcot, 
Plate V., fig. 57) is so formal, and the spines, as represented, are so formless compared 
with those constituting the most conspicuous feature of the ‘ Discovery’ specimens, 
that I failed at first to recognise that I was dealing with the same species. 
Consequently I drew up the above detailed diagnosis and prepared the accompanying 
figures (Plate II.), before establishing the identity of my specimens with Sluiter’s 
species. As Dr. Sluiter’s lithographer has scarcely done justice to his subject, and as, 
moreover, there are some points of difference in detail between the figures of the 
‘Charcot’ specimens and ours, I believe it will be useful to science that this present 
account of the ‘Discovery’ specimens should be published as a supplementary 
description of the species. 
I would point out:—that Plate IL, fig 1, gives a much more life-like 
* Bull. Mus. Nat. Hist. Paris, xi. (1905), p. 473. 
+ Expéd. Antarct. Frang. (Charcot). Tuniciers, p. 40. [No date—Ep.] 
