188 Bulletin, Vanderoilt Marine Museum, Vol. IV 



The sessile arms are in the order of 3, 4, 2, 1 ; the fourth pair are 

 nearly equal to the third, whereas the second pair are more than half 

 an inch shorter than the third, and the first pair are quite five-eighths 

 of an inch shorter than the second. The dorsal and lower lateral 

 pairs of arms each have a definite dorsal keel, which is thin, laminate, 

 more conspicuous on the distal half of each arm. There is also along 

 both lateral margins of all four pairs of sessile arms a marginal mem- 

 brane that is about as high as the adjacent suckers and which has 

 a series of transverse ridges formed by a strong muscle band, one on 

 each side of each sucker. The suckers on the sessile arms are in two 

 rows, but in some places they are so crowded as to appear in three 

 rows, and extend quite to the tip of the arms. The suckers on the 

 dorsal and ventral pairs of arms are very small, those of the upper 

 lateral arms are intermediate in size between these and those of the 

 upper lateral arms. The largest of these latter suckers are smaller 

 than the largest suckers of the tentacular arms. A typical sucker of 

 the sessile arm is figured. The suckers are distinctly cup-like, very 

 oblique, the outer side more swollen, the rim muscle thickened, with 

 a little pointed incision ; the ring is set with subequal, distally tapered, 

 bluntly rounded teeth. 



It is quite impossible to estimate the true length of the tentacular 

 arms from the dead specimens before me. The proximal part of the 

 arm is laterally compressed, with a distinct dorsal carina, which on 

 the distal half of the club broadens into a web-like lamina. There is 

 also a carina proximally on the ventral margins of the arm, which for 

 nearly an inch immediately below the club is divided by a narrow 

 groove, the margins of which anteriorly pass into the marginal mem- 

 brane, which is as high as the adjacent suckers and ribbed between 

 each sucker by a strong, transverse muscle fiber that does not extend 

 to the extreme edge of the membrane. The suckers are arranged in 

 four closely crowded rows; the proximal two or three of each row 

 being quite small, graduating in larger ones, of which there are about 

 ten, followed by four or five successively smaller ones, beyond which 

 there are five or six very minute suckers, extending quite to the tip of 

 the arm. The dentition of these very small suckers is rudimentary. 

 The larger suckers (one of which is figured) have the marginal ring 

 thickened with a narrow incision or "lip" on the outer side. The 

 chitinous ring has the teeth longer on the outer half, sharp, triangu- 

 late ; on the inner half they are similar but not so long. 



