Gatty Marine Laboratory, St. Andrews. 141 
to have been smooth during life. They are thus all con- 
siderably longer than in Roule’s form. 
The body is probably about 10 or 12 inches in length, 
rounded anteriorly and somewhat flattened posteriorly where 
it tapers to the tail, which has two long and strong caudal 
cirri. The dorsal cirri are conspicuous anteriorly for their 
size and length. 
The branchize commence on the 7th foot as a tuft of three 
processes. At the 10th there are by dichotomous division 
five or six filaments proceeding from a common stalk, and 
thus differing from the semi-pinnate type. At the 20th foot 
nine divisions occur, the 25th eight, but three are formed by 
a bifurcation of the tip of one of the longer processes. The 
30th has six, and they are now arranged in a semipinnate 
manner ; the 40th has five; 50th, three; 60th, three; 70th, 
two; that before and that behind three ; 80th, three. In the 
posterior region, again (of a separated fragment), an increase 
seems to occur, since four is the average number till within 
about half an inch of the tail. These branches spring from 
a common stem, and in the preparation spread over the 
dorsum, though sometimes three arise together and one 
separately. They continue almost to the posterior end, the 
3rd foot in front of the tail having a single short branchial 
process. 
In Roule’s form the branchi# commence on the fourth 
segment, and in the 40 to 50 anterior segments have about 
seven branches. In the segments behind these they diminish 
to four, three, and two to the posterior end. ‘There are thus 
considerable differences in the number and arrangement of the 
branchiz in the two forms, both anteriorly and posteriorly. 
The maxille (woodcut, fig. 2) have a flat curve, only well- 
marked at the tips. They are deep chocolate-brown, and 
are boldly separated from the flattened spathulate appendages 
posteriorly. A double interlocking apparatus exists pos- 
teriorly, and the inner edge of each blade is sharp. Each 
fits into a hollow in the great maxillary plate, and thus the 
rigidity of the parts after seizing prey is maintained. The 
great plates have five strong teeth anteriorly, followed by 
one or two minor points, the edge behind (about half the 
length of the organ) being smooth. The left azygos plate 
has nine teeth, the curved plate in front of it five teeth, and 
the two continuation-plates a denticle each. The anterior 
curved plate on the right has ten teeth, and the continuation- 
plates—larger and smaller—a denticle each. The mandibles 
have two strong shafts which are slightly movable on each 
other, and are coloured blackish brown externally, paler 
