MALDANID^]. 295 



b. Anal segment patelliform without cirri, the anus on a cone in the centre. Leio- 

 chone, Grube. 



c. Anal segment with a concave foliaceous plate without cirri. Anus opens on its 

 surface. Petaloproctus, De Quatrefages. (Nichomachella, Levinsen.) 



d. Anal segment obliquely truncated with neither plate nor funnel ; anus sub-dorsal. 

 Lumbriclymene, Sars. (Praxillura VerrillP). 



2. Ventral crotchets on all the setigerous segments. Paraxiothea, Webster. 



Racovitza 1 (1895) criticises the opinion of De Quatrefages 2 that the cephalic lobe is 

 reduced to a minute mass comparable to that in Arenicola, only soldered to the buccal lobe. 

 The brain is small, bilobed, and gives off posteriorly two minute twigs (nuchal nerves, 

 Racovitza), which with five or six other connectives to the proboscis probably represent 

 the stomato-gastric system. Semper, 8 again, describes supra-oesophageal ganglia and the 

 connectives united with the epidermis from which they are little separated. Ehlers holds 

 that the cephalic lobe is formed of the cephalic plate, which is always soldered to the 

 first segment. The views of De St. Joseph were similar. 



Racovitza groups the Maldanidse under three heads or types : (1) The cephalic lobe 

 has a palpode : ex. Leiocephalus leiopygos, Grube. (2) The cephalic lobe has a palpode 

 and a cephalic plate, Clymene lumbricoides, Milne Edwards. (3) The cephalic lobe has 

 neither palpode nor dorsal cephalic plate: ex. Petaloproctus spatidatus, Grube. The 

 cephalic ganglia are small, situated behind the palpode, when present, and give off the 

 oesophageal connectives which are superficial, and a nuchal nerve on each side. He 

 thinks that the primitive nerve-cell was bi-polar — one end superficial and the other basal. 



Orlandi (1898) describes the segmental organs in Clymene palermitana, Grube, as 

 somewhat clavate in outline with a funnel-shaped nephrostome communicating with a wide 

 tube which gradually diminishes to the nephridiopore. He 4 (1898) gave a description of the 

 Maldanids of Naples, prefacing his account with general remarks and the classification of 

 De St. Joseph. Besides four known species, he describes three new forms under the 

 genus Clymene, the only one he mentions. Thereafter he gives a brief account of the 

 structure of the dermal tissues, the muscles, nervous system, alimentary canal, vascular 

 system, segmental and reproductive organs. 



The same author 5 (1903) has described the reproduction of the anterior and posterior 

 regions in several forms such as Clymene collaris, Claparede, and other species at Naples. 



In an interesting paper on the nervous system of two species of this family, viz., 

 Axiothea torquata, and Clymene producta, Miss Lewis 6 (1898) gives details of the giant 

 nerve-cells and Leydig's fibres (neural canals or giant- fibres). The presence of a 

 centrosome and sphere is mentioned in the giant-cells, and also the eccentric position of 

 the nucleus. The sense-organs of the skin are also minutely described. 



One of the most recent as well as one of the most important classifications is that of 



1 'Arch. Zool. exper./ ser. iii, vol. iv, p. 227 et seq. 



2 f Hist. Nat. AnneL, t. ii, pp. 229-293. 



3 ' Arch. Zool. zoot. Instit. Wurzburg/ Bd. iii, p. 147. 



4 f Atti Soc. Ligust. Sci. Nat. e Greogr. G-enova/ vol. ix, p. 1, Tav. v— viii. 



5 Ibid., vol. xiv, 1903. 



6 ' Proc. Amer. Acad. Arts and So./ vol. xxxiii, p. 225, pis. 1—8. 



