284 CAPITELLA. CAPITATA. 



The winged books have two minute spines above the main fang. The same arrangement 

 is continued to the posterior end of the animal, though the caudal hooks are smaller. 



Habds. — A constant series of contractions from behind forwards keeps the coelomic 

 fluid in active motion. 



Reproduction. — Lo Bianco gives the reproductive period as from November to May at 

 Naples. 



J. P. Van Beneden 1 (1857) described the structure of this species, which he found 

 inhabiting delicate tubes under stones between tide-marks. He figures the ripe male and 

 female, the testes in the former occurring laterally in front of the genital hooks. The 

 ovaries occupy a similar position in the female. The larva resembles that in Plate XCIII, 

 fig. 10, and has two eyes and coarse globules (yolk) internally. 



Dr. Johnston (1865) included Gapltella under his Lumbricida3, but his description 

 shows that he refers to this form, which he found on the seashore in wet, gravelly places. 



Claparede 2 (1863) describes the segmental organs in G. rubicunda, Keferstein, as pear- 

 shaped, yellowish bodies, with an opening into the body-cavity and another on the dorsal 

 surface between two lip-like papilla, bearing palpocils. They are present in each body- 

 segment. 



The same author (1868) states that in the Hebrides he found examples with simple 

 hooks whilst those from Naples had bifid hooks, the figure showing two spines above the 

 great fang in lateral view. The eyes are present throughout adult life, though not always 

 easily seen. In the young they are distinct and furnished with lenses. He notes that in 

 the adult females at Naples the first six segments have four bundles of subulate bristles 

 only ; the seventh has its external bundles subulate, but the internal bundles have subu- 

 late bristles externally and crotchets internally. The eighth segment has only crotchets. 

 In the male the first six segments have only subulate bristles; in the seventh segment the 

 external bundle is composed of ten crotchets with perhaps a single subulate bristle inside, 

 the crotchets outside. The eighth and ninth segments have only crotchets in the external 

 series, the internal bundles being modified to form the copulatory apparatus. In the tenth 

 segment the four bundles are formed exclusively of crotchets. It is interesting that in 

 the young forms (after hatching) only three segments with simple bristles occur, and such 

 is the condition for a considerable time. By-and-by, according to Claparede, bristles 

 appear in the fourth segment in the place of the hooks. The sexual apertures of the 

 female form transverse clefts on the ventral surface between the seventh and eighth 

 segments, a little within the external fascicles of bristles. 



Claparede and Mecznikow (1868) found the adults ripe during the winter at Naples. 

 The youngest larva is elongate-ovoid with prototroch and telotrocb, two eyes, and an 

 alimentary region. The next stage has a conical snout and about a dozen body-segments, 

 the buccal being the longest — with mouth and pharynx. The posterior region is bluntly- 

 conical. When 1 mm. in length, the body is much more elongate, the snout and tail 

 more pointed, the eyes have lenses, and sense-organs occur behind them. The pharynx 

 occupies the buccal, the next, and part of the second bristled segments, then a narrow 

 oesophagus leads to the stomachal region, behind which is the moniliform gut terminating 



1 'Bull. Acad. Roy. de Sci. Belgique/ 26th year, 2nd ser., t. iii, p. 137, two plates. 

 3 'Beobacht. Anat. Entwickl./ p. 27, pi. xv, figs. 5, 8, and 9. 



