TUNICATA. 11 



This little species of Boltenia seems distinct from all other known species. It 

 (lirt'ers from the two species of the ' Charcot ' expedition in liiiving but few l)ars in 

 the interspace between two branchial folds, in the condition of the dorsal lamina, and 

 in other details of structure; and from B. bouvdcnsia, ilichsn., of the ' Valdivia ' 

 Expedition, in the number of branchial folds and in the structure of the dorsal tubercle. 

 The minutely spinose surface of our species is also a notable peculiarity. 



In tlie same bottle with the.sc .specimens of Boltenia is a single specimen of 

 a flattened, smooth Cynthiid (Plate VII., fig. 12) with 4-lobed apertures (fig. 13), 

 which is in such bad condition that further identification is impossible. *The muscles 

 of the mantle are the only internal organs that can be seen under the microscope. 

 Possibly the animal may have Ijeen dead and decaying when collected. 



MOLGULID.E. 



MOLGULA HODGSONI. 



(Plate in., figs. 7-13.) 



Locality. — Winter Quarters, in McMurdo Bay, 10 fathoms, 22.iii.02 ; one specimen, 

 4 X 2 • 2 X 2 cm. 



External Appearance. — Body pyriform, with a wider anterior and a narrow pointed 

 posterior end (Plate TIL, fig. 7). Apparently not attached, or only very slightly so, by 

 the posterior end. Atrial aperture terminal. Branchial a short distance back along 

 the dorsal edge (fig. 7); both are on prominent siphons. Eiglit-haud side more 

 flattened and left side more swollen and rounded. Whole surface slightly roughened, 

 with a sparse coating of sponge spicules and occasional shell-fragments and other 

 foreign bodies. Colour a warm grey, becoming browner at anterior end. 



Test thin and membranous, but moderately tough, translucent, free on left side, 

 but attached to mantle over the more muscular right side. 



Mantle rather trau.sparent, but moderately muscular, the bundles being few, but 

 very distinct (figs. 8 and 9). 



Branchial Sac with seven folds on each side, with four very wide bars on the 

 fold, and four or five liars in the interspace ; occasional very wide transverse vessels ; 

 stigmata curved and irregularly arranged, but never forming spirals or infundil)ula 

 (fig. 11). 



Tentacles much branched, of two sizes, six or seven of each. The tentacles 

 rather slender, with long delicate l)ranches. 



JJinsal Lamina a plain narrow mcml»rane, with no ribs nor marginal teeth. It is 

 short, and rather inconspicuous. 



Dorsal Tubercle broadly cordate in shape (fig. 10), with both entls turned spirally 

 inwards and the opening between them directed posteriorly. 



