128 Proceedings of the Royal Irish Academy. 



suggested that Polysiphonia (uberosa, Hertwig, might he an Aetinernus ; but 

 it is really quite a distinct form, and more related to Actinostola, as I hope 

 to show in another place. 



1 1. A saginatus Verrill. 



(PI. XV, figs. 4 and 0; PI. XVI. figs. 1-10; PI. XVIII, figs. 2-7 and 10.) 



Helga cxx. Aug. 24, 1001. 77 mil.- W.N.W. of Ac-lull Head. 3S2 

 fathoms. 1 specimen. 



Measurements. — Diameter <>i tin- basal fissure when opened, l - 7cm.; of 

 contracted oral disc, 5"5cm.; of expanded disc and tentacles, 11-3 cm.; 

 length oi basal fissure, 7 4 cm. : of mouth, 4 cm. : of a large tentacle, 2*7 cm. ; 

 height "f column, (i cm. 



A characters — Pedal disc formed into a lung, deep, and narrow 



crack, which oml long spine belonging t<> some other animal. Con- 



tently the pedal disc i- as long as the diameter of the body, hut not 

 nearly as wide; its edges wrap themselves round the spine, and meet each 



other, hut do not i'us.- save at nd. The body is whitish, and perfectly 



shapeless, tin- oral disc and tentacles being partly incurved and hidden. Its 

 wall forms .i soft, thick, jelly-like coat, like the test of an Ascidian, which 

 i- smooth hut for irregular pits and furrows. The margin is continuous 

 with the basal Bwellings of the outei tentacles. The long, slender tentacles, 

 tapi - dually to a point, and the disc, are pale salmon. The tentacles 



stiff enough to support themselves, and tin- rather thin disc lias, as usual, 

 radii corresponding to the tentacles, which do not reach tin- wide mouth, 

 witli its soft lips. As the animal i> preserved, the disc is infolded, hut it can 



opened out, and it then exceeds the column, and, though not truly circular 

 in outline, is only i at her irregularly wavy, not definitely lohed. The tentacles 



137 in number, and are arranged in two alternating cycles only (sixty- 

 : d, the rest non-marginal) at the extreme edge of the disc, even 

 the inni ommuni c tore oi less with the margin. It seems to 



me that in this case it would l>e imagination to divide the inner tentacles 

 into more than one cycle. They are all, allowing foi the undulate outline 

 of the disc, approximately on one level, and all Bub-marginaL All the 

 tentacles have basal swellings of mesogloea (PL XV, fig. 9), which vary in 

 size in individual cases, but are on the whole larger on the outer than the 

 inner ones. The tent iclea themsel rather uneven in si/.e, a few being 



aborted, but are on the whole sub-equal. For general appearance, see 



:.' . — Only six pairs of mesenteries are perfect, a nd 



n these are not all equally so. There are five -ixty-scven pairs), and 



