TUNICATA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 89 



the characteristic smooth test and translucent grey tint, and they also agree closely 

 in internal details with the Challenger specimens from shallow water off the Falkland 

 Islands. 



MICHAELSKN has suggested that this species and Paramolgula gigantea (Cunningham) 

 are the same. No doubt they are related forms ; both belong to the restricted genus 

 Paramolgula, having only broad, ribbon-like longitudinal bars but no true folds in the 

 branchial sac (a fact I overlooked in drawing up my " Revised Classification of the 

 Tunicata" in 1891, as MICHAELSEN has pointed out), but I do not consider them as 

 identical. In addition to differences in the external appearance the shape and the 

 condition of the test the branchial sacs are not alike in detail, and the dorsal tubercles 

 differ widely. I give here a figure of the dorsal tubercle (Plate, fig. 9) of P. gregaria 

 from the Scotia collection for comparison with that of P. gigantea figured in the 

 Challenger Report. 



LESSON figures his species with five lobes round each aperture, but that is no doubt 

 an error. The branchial aperture has six and the atria! four lobes. 



Paramolgula horrida (Herdman) (?). (Plate, figs. 10 and 11.) 



Locality. Station 118, on hulks, Stanley Harbour, Falkland Islands. 



I have very little doubt that this single large specimen (measuring 7 '5 cm. in length 

 and 5 '5 cm. in breadth) belongs to the same species as the specimen from "off the 

 Falkland Islands, 5-12 fathoms," which I described in the Challenger Report as Molgula 

 horrida. They both fall within the more modern genus Paramolgula, separated off 

 from Molgula by TRAUSTEDT because of the absence of true folds in the branchial sac. 

 As the Challenger description was drawn from a single specimen, and as this Scotia 

 specimen differs a little in detail, it may be well, in the interests of a fuller knowledge 

 of the species, to add a few of the characteristics of the individual before me. 



The shape is irregularly ovate, and flattened, and the colour is a very dark 

 brown. The other external characters can be seen from the figure (Plate, fig. 10). 

 The Test is leathery and rough on the surface. It is thin but tough, and dark 

 but smooth and glistening on the inner surface. The Mantle is dark brown and 

 opaque. It is thick, but soft and not muscular, or at least the muscles do not form 

 obvious bands. 



The Branchial Sac has on each side seven wide longitudinal vessels which look like 

 narrow folds. Between the distant wider transverse vessels, narrower intermediate ones 

 branch in all directions in a dendritic manner, so as to form rounded and oval and 

 variously shaped meshes in which the stigmata lie. The stigmata are also rather 

 irregular in arrangement, being in some parts in spirals and in other places side by side 

 in rows (see fig. 1 1 ). 



The Tentacles are of different sizes, there being eight larger much branched, with 

 some smaller ones between. 



(ROY. soc. EDIN. TRANS., VOL. XLVIII., 307.) 



