AUTOLYTUS. 209 



Head somewhat like that of 8. armillaris, except that the median tentacle is longer 

 (forty-four segments) and the palpi seem to be closer. The paired tentacles have fifteen 

 segments. 



The incomplete body has sixty-four segments and is 18 mm. long, the breadth being 

 1*5 mm. The colour of the dorsum (in the spirit-preparation) is brownish-yellow. The 

 first segment bears two tentacular cirri, the dorsal very long. The proboscis (pharynx) 

 has a single tooth and reaches to the thirteenth segment. 



The foot has a long dorsal cirrus of forty or fifty segments. The setigerous region is 

 short and blunt — carrying bristles with a somewhat long terminal piece and a simple hook 

 at the tip, and thus resembling those of 8. armillaris. The ventral cirrus is short and 

 clavate, a little longer than the setigerous region (Ehlers). 



How far the cirri vary in length is still an open question, so that the species may yet 

 be linked on to others. 



Group IV.— AUTOLYTEA. 



Syllideans deprived of ventral cirri. Palpi little developed, soldered on the ventral 

 surface of the cephalic lobes. Cirri not articulated. Reproduction generally by stolons 

 (schizogamy), rarely direct (epigamy, Malaquin). 



Genus LV. — Autolytus, Grube, 1851. 



Animal surculare. — Head rounded in front; palpi obsolete (coalescent), but separated 

 by a line ventrally. Proboscis sinuous, with a crown of teeth. Stomach little developed. 

 Tentacles three, smooth, and little tapered. Two tentacular cirri on each side of the 

 buccal segment. Dorsal cirri of the first two segments considerably longer than the 

 others. Ventral cirri absent. Falcate bristles with short bifid tips, the lower point or 

 hook being the larger. The sexual generation budded from the foregoing shows dissimilar 

 males and females (Polybostrichus and Sacconereis), but both always have a median 

 tentacle, and the paired tentacles are often present. 



In a transverse section of a female (Fig. 56) the muscular system is as powerfully 

 developed as in Syllis, the dorsal longitudinal muscles widening from the median raphe 

 to the inferior border. The ventral longitudinal muscles are curved, and separated by 

 the large nerve-cords. The large ova lie in the cavities of the feet and in the peri- 

 visceral space around the gut, which in the example had thick glandular walls. 



The type of circulation in this group is simple, a dorsal and a ventral vessel united 

 only in the anterior region, as seen in Autolytus and Myrianicla, are present. The nurse- 

 stock in the latter has a dorsal vessel fixed to the wall of the body by the mesentery, and 

 in a fold of the intestine, though quite free from it (the intestine). The ventral vessel is 

 intimately united with the intestine. In the anterior region the vessels are independent 

 of the proboscis dorsally and ventrally. The dorsal vessel is only contractile anteriorly 

 (Malaquin) . 



84 



