12 ANTARCTIC MARINE 



in the anterior two-fifths of the tail. The elongated renette-cell, two and one- 

 half times as long as the body-diameter, and one-fourth as wide a? long, lies a 

 little in front of the cardia, and is not re flexed. The excretory pore is somewhat 

 behind the pharynx. Distinct nerve-cells, more numerous behind the ring, are 

 arranged (at least in front of the ring), in six longitudinal groups. The cylin- 

 drical part of the tail is about one-tenth as wide as the base. 



The slender, uniform, but rather strong spicula, as wide as the narrowest part 

 of the tail, are twice as long as the anal body-diameter, and lie with their proxi- 

 mal ends dorsal to the body axis. The proximal eighth of each spiculum is sep- 

 arately more or less arcuate, so that one may speak of a curved cephalum or 

 proximal end. Two separate accessory pieces, rather frail, bent at the distal 

 end, one-sixth as long as the spicula and parallel to them, form a rather close 

 collar round the distal ends of the spicula. On each side of the b'ody there are 

 four equidistant, ventro-submedian, pre-anal, papilla-like setae, one-sixth as 

 long as the body-diameter, extending in a row from near the anus to near the sup- 

 plementary organ. There are about three ventro-submedian post-anal setae on 

 each side of the middle part of the tail. 



Habitat; remarks. Cape Royds; Bay, Cape Royds. One adult and several 

 immature somewhat shrunken specimens. This species differs from A. similis in 

 having five pectoral hairs, longer setae, a sub-cyliridroid pharynx, and an 

 oesophagus without expansion behind the nerve-ring 



APLECTUS, new genus 



Species of this newly proposed genus have the general form of Plectus, but have 

 the phar3iix less definitely developed, and the renette-cell farther back and not 

 reflexed. They differ also in having nearly obsolete lips, and a nearly cylindroid 

 oesophagus whose small cardiac bulb is without a three-fold striated valve. The 

 spinneret also differs from that of Plectus, as shown in the sketch. The male 

 supplementary organs in the two genera also differ materially. These facts 

 together with the marine habitat and the relative abundance of the males of 

 Apleclus, appear to make necessary a separate genus for the reception of this 

 antarctic species. The following is the type species. 



3. Aplectus antarcticus, n.g., n. sp. The rather thin cuticle is traversed by 

 about 700 duplex striae, which give the contour an obscurely doubly crenate 



appearance. Two wings, separated 



! 12 : e - 2I> . . . '. 51 ' . . . 87 : , e,, b y a distance about equal to the width 



y^jj .8 2.2~^ 2.3, 2.4 1.9 ' O f an annule, begin near the middle 



** -Q . : si of the neck and end near the middle 



H/ '....:. -r;r..: ' > .6mn. of the tail. Cervical setae, similar 



to the cephalic setae, occur one or two 



on each lateral line; and on the male tail there are setae, one-third to one-eighth as 

 long as the body is wide. The lips are very small and difficult to observe. The 

 pharynx, very inconspicuous and hard to distinguish, is probably double, the 

 narrow, tubular, anterior part extending to a little behind the amphids, the pos- 

 terior part, which closely resembles the oesophagus, extending nearly halfway 

 to the nerve-ring where there is a break in the musculature. In the lateral view 

 there are seen close behind the cephalic setae, under the cuticle, very minute 



