308 



LAGISCA EXTENUATA. 



Head somewhat hexagonal (Plate XXVIII, fig. 2), with a deep median groove at 

 the base of the tentacle, and two prominent peaks, each of which is at a distance from 

 the tentacles. The eyes are comparatively large, and, judging from the conditions of the 

 largest example, increase with age and depth of water. Two slightly smaller are situated 

 in front of the nuchal collar, and look dorsally, and two somewhat larger rather in 

 front of the middle of the head, and lateral in position. In the example with the large 

 eyes (from 690 fathoms) the anterior pair show traces of a corneal lens. The median 

 tentacle is somewhat long, scarcely dilated below the filiform tip in the preparations, and 

 covered with moderately long cilia having a slightly bulbous tip. The lateral tentacles are 

 short, but also have attenuate tips. The tentacular cirri are similar to the median 

 tentacle. None of these organs show any signs of pigment in the preparations. The 

 palpi are of moderate length, and have rows of minute conical papillae, as De St. Joseph 

 also found, whereas Marenzeller observes that their upper surface is smooth. In the 

 British forms one prominent papillose ridge occurs dorsally. 



Body. — Somewhat narrow and elongated, slightly tapered towards the head, and 

 very gradually towards the tail. Forty-five segments bear bristled feet, and the tail is 

 not quite complete. Behind the distension caused by the included proboscis, the 

 segments are boldly marked by the lozenge-shaped transverse bars which stretch 

 between the bases of the scale-pedicles, or their homologues in the other feet. Each 

 segment thus shows an anterior and posterior paler belt, and a median darker area. 

 Traces of brownish pigment occur posteriorly at the bases of the feet and on the 

 lozenge-shaped transverse bars. In some the brown pigment is broken into a number 

 of symmetrically placed touches, two of which are on the bases of the feet, and 

 the rest in interrupted bands across the segments. Ventrally traces of pigment occur 

 on the lips/ and the median iridescent depressed band is well marked. The conical 

 segmental (nephridial) papillse at the posterior border is directed upward between the 

 feet. A considerable portion of the body posteriorly is uncovered by scales. 



De St. Joseph states that there are only seventeen papillas at the margin of the 

 proboscis, but so far as can be seen there are nine in each half. 



Fig. 24. 



Edge of scale of Lagisca extewuata, Grube. 



