AUTOLYTUS PICTUS. 213 



less white. The ventral surface is pale or flesh-coloured. The tints are retained for 

 a long time (eight months) in spirit. 



The proventriculus, according to De St. Joseph, has from forty-eight to sixty rows of 

 brown points, and occurs in segments 10 and 11. The proboscis, he states, is furnished 

 with ten large teeth, alternating with ten smaller. He also found in the sub-cuticular 

 tissue greyish plates with two refringent hemispherical concretions. 



The foot (Plate LXXI, fig. 2) carries the dorsal cirrus, which in the fourth 

 segment exceeds in length the tentacles and tentacular cirri. They are short posteriorly. 

 All have palpocils, and show slight folds and crenations when coiled. As in Amblyosyllis 

 they are stretched out on irritation. When falling through the water the long coiled 

 processes in front bear the weight on touching the bottom. The setigerous process is 

 somewhat short and truncated at the tip, though it varies in outline according to the 

 development of the reproductive elements. It has several spines, which point above the 

 bristles. The latter (Plate LXXIX, fig. 21) are comparatively short, with a stout, slightly 

 curved shaft, the distal end of which is enlarged, and both sides of the bevelled region 

 have minute spines, largest at the apex. The distal piece is short and rather broad, and 

 the tip is bifid, the lower hook being the larger. Towards the tail only a single conspicuous 

 spine occurs in each bristle-bundle, and finally a larger and a smaller spine alone exist. 

 The terminal processes of the bristles vary much in length, being very short in the 

 anterior region, then lengthening, and again becoming short as the bristles diminish in 

 size towards the tail. The ventral cirrus seems to be fused with the setigerous lobe. 



In the thirty-fourth segment De St. Joseph met with a single dorsal bristle, " a article 

 en alene," as figured by Langerhans, who found it on the fourth foot. 



He also found individuals bearing eggs, as Ehlers and Claparede did, but he thinks 

 Claparede was hasty in concluding them to be Autolyti without alternation of genera- 

 tions. He observed eggs in the thirteenth segment and in the fifteenth segment (with a 

 developing head of a bud). The buds have from forty-five to' fifty-eight segments. In 

 the males (Polybostriehus) the first region has six segments, the second thirty-one segments, 

 and the third twenty-two segments. The first region has two spines in each foot ; in the 

 second the compound bristles are accompanied by a strong spine, except the two first 

 segments, which have two, and the natatory bristles are accompanied by two hooked 

 bristles ; in the third region there is only one spine. 



No proboscis or proventriculus occurs in the buds, and the intestine is rudimentary. 



Malaquin observes that the first three setigerous segments (devoid of swimming- 

 bristles) carry the male elements. The rest have no genital glands, but have long 

 feet and swimming-bristles. The latter have specially-developed muscles — two superior 

 and two inferior — for moving them. 



Reproduction. — The male buds (Plate XL VII, fig. 3) of this form are procured in May, 

 and are composed of three regions. The head and two achaatous segments and all their 

 appendages are pale. Of the great bifid palps the large inner division is ciliated and 

 tapered, the outer slender and non-ciliated. Two minute rudiments occur in the central 

 region behind these. The median tentacle is long. The eyes are large, and appear to lie 

 on the ventral rather than on the dorsal surface, and are bright red. The anterior pair are 

 the wider apart, much (more than twice) larger than the posterior, and nearly circular, 



