10 W. A. HERDMAN. 



the description given by Michaelsen (JB. Hamburgisch. wiss. Anstalten, XXV., 

 2 Beiheft, 1908, p. 250). H. clavigera has been recorded from various parts of the 

 South American coast, Peru, and Chili. 



The photograph from which the larger figure (Plate IV., fig. 7) is taken 

 represents the single specimen about twice the natural size. 



BOLTENIID^E. 



BOLTENIA SCOTTI. 



(Plate VII., figs. 1-11.) 



Locality. Winter Quarters, in McMurdo Bay, Feb. 1902. 



External Appearance. Stalk from one-half to three times as long as body, 

 attached by an expanded base to a fragment of stone, and tapering slightly upwards 

 (figs. 1, 3, 5). Body rather longer than broad, of ovate sub-cylindrical form, the 

 anterior end, where the stalk is attached, being the wider. Apertures distant, the 

 branchial being nearly under the stalk (figs. 1, 3) and the atrial in the middle of 

 the free posterior end of the body ; both apertures sessile and cross-slit (figs. 2, 4). 

 Surface of the body finely roughened all over with minute papillae, ending in sharp 

 spines (figs. 7 and 8) ; surface of stalk corrugated or wrinkled. Colour grey, nearly 

 opaque ; stalk rather yellowish. Size of largest specimen (fig. 1) : Body 1 "5 cm. long, 

 1 cm. broad ; stalk nearly 4 cm. long. 



Test, thin but tough. The roughness on the outer surface (fig. 11) is seen 

 under the microscope to be due to closely placed, minute, sharp-pointed spines 

 (fig. 8) of a yellowish tint. Eound the apertures the spines are depressed and point 

 radially outwards (figs. 4 and 6). 



Mantle thin, but moderately muscular, closely adhering to the test. The thin 

 muscle bundles are in most parts arranged with regularity, so as to form quadrangular 

 meshes. 



Branchial Sac with six folds on one side and seven on the other. There are 

 seven to ten bars on a fold, and one or two in the interspace between (fig. 10). 



Dorsal Lamina composed of a series of short triangular languets, united by their 

 bases to a wide membrane (fig. 10). 



Tentacles compound, about eight larger, rather slender and feathery, and some 

 much smaller ones between. 



Dorsal Tubercle small, but prominent, on a rounded elevation ; cordate, with both 

 horns coiled inwards (fig. 9). The long nerve ganglion is visible behind and to one 

 side of the dorsal tubercle. 



Alimentary Canal very slender, forming a long narrow loop. Stomach globular, 

 with longitudinal folds ; intestine narrow and straight for the greater part of its length. 



Gonads small, on both sides of the body. 



