CAPITELLIDJE. 273 



springing from the ganglia of the nerve-cords, and gives details of the structure of the 

 eyes, which show cuticle, long cuticular cells (Hautfadenzelle), refractive cells, and 

 nucleated fibres leading to ganglion cells. The ciliated organ lies in the groove between 

 the cephalic and buccal segments, and is protruded as a rounded papilla from a sac 

 on each side. The author next describes the ciliated side-organs 1 of the thorax and 

 abdomen, pointing out their varying position in thorax, anterior, middle, and posterior 

 regions of the abdomen. From without inward he shows sensory hairs beyond the cuticle, 

 rod, granular spindle, nerve-fibril to hair retractors, nerve-fibrils to various ganglia 

 intervening between the spindle and the spinal nerves. The cup-shaped (becherfor- 

 migen) organs of the head, proboscis, and the thorax are likewise sense-organs. The 

 structure of the feet, segmental organs, reproductive apparatus, ccelom, and blood 

 (hgemolymph) is likewise given. 



The author then treats similarly, but more briefly, of Dasybranchus, Mastobranchus, 

 Heteromastus, Gapitella, and Gapitomastus. He next contrasts the structure of the groups 

 with that of other annelids, but though he cites Polygordius, Sagitella, the Oligochaots, 

 Planarians, Coelenterates, Echinoderms, Peripatus, the Myriapods, Molluscs, and 

 Vertebrates, he does not mention the Nemerteans. A description of the various species 

 occurring in the Neapolitan fauna is followed by a notice of those not included in it, whilst 

 a comparison with other groups of Chsetopods concludes the work which is an honour 

 both in text and in plates to Naples and its Zoological Station. 



Eisig 2 describes several nervous centres which Racovitza thinks are homologous with 

 his middle and posterior regions of the brain. 



Cuenot 3 (1891) maintained that in Dasybranchus and other forms the coelomic 

 corpuscles were formed in two red tubes which lie on the ventral surface between the 

 intestine and the skin. He describes the tubes as having small septa and their walls covered 

 with cells representing the coelomic corpuscles in development. This observation is in 

 need of confirmation. 



The Capitelliformia constitute the fourth sub-order of Benham's 4 (1896) JNereidiformia 

 {more Levinsen) which he places between the Amphictenidas and the Opheliidas. They 

 appear to be more naturally placed between the Cirratulidse and the Maldanidse, as 

 Malmgren formerly held. 



Eisig 5 (1899) carried out an elaborate investigation on the development of this group 

 from the period of fertilisation onward through the various quartettes of the micromeres to 

 the division of the macromeres and the fate of the statoblasts, to the development of cilia 

 on the larva and its escape as a trochophore, and thereafter its further growth to the 

 third or fourth week. Every tissue was carefully investigated by this distinguished 

 observer, and the various views with regard to cell-lineage were carefully weighed. 



Gravier 6 (1901) describes a sub-genus of Notomastus (Clistomastus, Eisig) as occurring 



1 Except in Capitella, p. 494. 



3 ' Capitelliden/ p. 906, pi. xxxvii. 



3 ' Arch. Zool. exper./ ser. 2, t. ix, p. 425, pi. xvi, fig. 13. 



4 Op. cit., p. 331. 



5 ' Mitt. Zool. Stat. Neapel/ Bd. xiii, p. 1, pis. i — ix. 



6 ' Bull. Mus. Hist. Nat./ Paris, t. viii, p. 402. 



158 



