ARICIDEA JEFFREYSII. 473 
latter gradually increase in size, and are long and slender in the posterior segments. 
Anal segment rounded, with three slender subulate cirri, two dorso-lateral and one median 
ventral ; a pair of cirri fixed to the anterior border, which may represent the last pair of 
dorsal cirri. Anteriorly the dorsal and ventral bristles are almost equal in length, and 
continue so to the posterior end in the immature, but in the mature male the ventral 
increase in length about the fifteenth to the twentieth segment, whilst the dorsal become 
shorter. The bristles of the male are more prominent than in the female, exceeding the 
width of the body, especially posteriorly. The dorsal cirri are placed behind the fascicle 
of bristles. Capillary bristles slender, devoid of wings, and the longer ventral bristles in 
the male are striated longitudinally. On the lower side of the front row of the dorsal 
tuft are one to three short bristles with lyrate tips, one end being longer than the other 
and with a row of spines on its inner margin, this type commencing in the fourth segment 
and continuing to the tail. In the fourth foot the dorsal bristles are slightly longer than 
the ventral; in the fiftieth foot the ventral are thrice as long. In the male the upper 
ventral bristles are longer and thicker as well as longitudinally striated—a condition not 
present in the female. In the eightieth foot the differences between the dorsal and 
ventral bristles are less pronounced. Red ova appear in the female in the twentieth 
seoment, usually four in each (Southern). 
SYNONYMS. 
1914. Paraonis lyra, Southern. Proc. Roy. Ivish Acad., vol. xxxi, No. 47, p. 94. 
1922. . » McIntosh. Ann. Nat. Hist., ser. 9, vol. ix, p. 14. 
Habitat.—Mature male in surface tow-net at night, Galway and Dingle Bays (Southern). 
The genus has a wide distribution, from Sweden southward. 
A typical bristle is shown in Plate CX X XVI, fig. 3. 
Genus ARICIDEA, Webster, 1879. 
Head with a sensory median process; two eyes; nuchal organs. Branchie only on 
the anterior segments. Feet biramous, dorsal cirri, ventral rami with cirri only on the 
anterior segments. Bristles simple, capillary ; first segment with bristles; no tentacular 
cirri. 
ARICIDEA JEFFREYSII, McIntosh, 1878. 
Specific Characters—Head bluntly pointed, and divided into three regions by two antero- 
posterior curved lines, which with the central region are marked with dark pigment pos- 
teriorly. In front of this is the somewhat short and clavate tentacle, which has a constricted 
base rising from an elevated portion of the snout. Body flattened from above downward 
and long. The first segment bears only the dorsal and ventral bristle-tufts; the second 
has, in addition, a dorsal cirrus, whilst the fourth has a branchial process. The branchize 
remain of considerable size (7.e., nearly meet in the middle of the dorsum) for eight segments, 
then diminish to the fifteenth, in which they are very small. Bristles simple and striated 
with wings, and they increase in length to the end of the fragment. 
