268 HERMIONE HYSTPIX. 



and the shorter and more slender bristles externally. Ventrally are three bristles having 

 above the fang respectively two, one, two spines. 



The thirteenth foot has dorsally scales and spines. Ventrally three bristles, the 

 hooks above the fang being respectively one, two, one. 



The fifteenth has scales and spines. Ventrally the two bristles have one spike 

 each above fang. 



The twentieth foot (cirrus-bearing) has longer and more tapered dorsal bristles, the 

 granules on which are less distinct, especially in the tapered forms. The shorter, broader 

 forms show the granules distinctly. Ventrally the three powerful bristles have only the 

 great fang. A typical foot is shown in Plate XXXVI, fig. 13. 



The terminal feet have dorsally the granular bristles more pointed and less curved 

 than in front, moreover the tips are smooth ; while ventrally the tips are more elongated, 

 and have numerous spines above the great fang. One of the smaller forms is X 90 in Plate 

 XXXVII, fig. 8. The ventral bristles of this form are much stouter than in Laetmatonice 

 filicomis. 



This species is specially subject to the attacks of Loxosoma, which occurs abundantly 

 on the ventral surface and cirri, on the feet, mouth, and other parts. Parasitic algas 

 often grow on the bristles and spines, with mud, sponge-spicules, and other debris 

 entangled. A remarkable hydroid creeping along the bristles is also present. Hydroids 

 and Polyzoa, indeed, are not uncommon. 



In habit this species appears to correspond with Aphrodita and Lsetmatonice. 



Reproduction. — The ova were well advanced in July in those from Herm and other 

 parts of the Channel Islands. Lo Bianco found the Neapolitan examples with developing 

 ova in October, and increasing in size in November. 



An interesting account of the development is given by Dr. P. von Drasche, 1 of 

 Vienna, from observations made at the rich Marine Station of Trieste. He found the 

 ripe forms in October and November, the latter month being probably that in which 

 deposition of the eggs generally takes place. The egg measures 0*2 mm., and he watched 

 it through all the stages of segmentation till the embryo moved within the capsule by aid 

 of cilia. It then issued as a pear-shaped trochosphere, with an equatorial circlet of cilia 

 and a tuft in front; while a solid mass of deutoplasm occurred in the middle of the body. 

 The violet-coloured larva soon acquires another ring of shorter cilia behind the first or 

 pre-oral, an anal ring of cilia appears, and it swims about actively. Two red eyes are 

 developed in front. The anterior end becomes triangular, and a characteristic broad 

 cellular collar lies behind the eyes — the mouth, with a tuft of cilia, opening towards (in 

 front of) its posterior border ventrally. On the fourth day the larva has increased in 

 size, and the yolk-mass has concentrated into a covering for the alimentary canal. On the 

 under surface of the snout are five small papillse — organs, however, not homologous with 

 the cephalic processes of the adult. There are now three segments with bristles. On 

 the sixth day it is still larger. The alimentary canal is complete. The equatorial belt is 

 smaller. There are five segments. The feet show a large yellow spine and bristles, the 

 latter having a structure conformable to the adult type, though the glochidiate forms 



1 'Beitr. z. Entwickelung d. Polychaeten/ pp. 7—11, Taf. ii, f. 8—20; and Taf. iii, f. 1—4, 



1885. 



