56 TELETHUSjE.- 



SubellidaB and before the Hirudinacea. He recognized the distinction of A. Loveni of the 

 Cape from the European forms. 



Levinsen 1 (1883) grouped the Telethusae with the Scalibregmida3 under the Areni- 

 colina, a natural arrangement for both families. 



V. Cams (1885) places the Arenicolida3 between the Scalibregmidao and MaldanidaB, 

 but adds nothing to previous knowledge. 



Viallanes 2 (1885) treats of the endothelium of Arenicola, which he considers pro- 

 tective, and points out that it passes into that covering the muscular fasciculi, and over 

 the diaphragm. 



An elaborate paper was written by Ehlers 3 (1892) on the auditory organs of 

 Arenicola marina, A. Olaparedii, A. Grubii, and others — accompanied by excellent figures. 

 In the case of A. marina the organ opens to the exterior and the otoliths are foreign 

 particles. In the other two species no duct exists, and the otocysts or statoliths are 

 secreted by the sac itself. 



The Arenicolidse constituted the third family of Prof. Benham's 4 (1896) third sub- 

 order — Scoleciformia of the order Nereidiformia. 



Fauvel 5 (1899) gave an interesting historical account of the " Arenicoliens " with 

 critical remarks, a description of their external morphology, coslom, alimentary, circula- 

 tory, and nervous systems, segmental organs, reproduction, habitat, geographical distribu- 

 tion, relations to Branchiomaldane, and phylogeny and affinities — illustrated by text-figures. 

 In this paper he holds Branchiomaldane to be only a synonym for the young of Arenicola. 

 Fauvel, like Claparede, thought A. ecaudata the most primitive form, and A. Olaparedii 

 he placed at the head of the series on account of its prostomial lobes, its cephalic ganglia, 

 the development of its sensitive palps, and its digestive system. He disagreed, with 

 Mesnil's view that the Arenicolidse and Maldanidae are closely related and might be 

 combined. 



Ash worth 6 has given a full and excellently illustrated description of Arenicola. He 

 thinks that the family has certain affinities with the Scalibregmidse and Opheliidse since 

 they have a spacious ccelom subdivided anteriorly by diaphragms, an eversible pharynx, 

 followed by an oesophagus with one or more pairs of lateral glandular outgrowths, a 

 dilated stomach, more or less freely movable, and a straight intestine, usually with a ventral 

 groove. Yet, after comparing the organs in each, he concludes that they are clearly 

 distinguished from these and the Maldanidaa. 



In his recent account of the Arenicolidse in the Museum at Berlin 7 he places reliance 

 in diagnosis on the number of the chsetiferous and branchiferous segments, the structure 

 of the branchiae, the relative size of the median and lateral lobes of the prostomium, the 

 absence or presence of the openings of the statocysts, the position of the nephridial pores, 



1 'Vidensk. Meddel. Foren. Kjobenh./ 1883, p. 180. 



2 'Ann. Sc. nat./ 6 e ser., t. xx, p. 20, 1 pi. 



3 'Zeitschr. f. wiss. Zool./ Bd. liii, Suppl. p. 219, pis. xi-xiv. 



4 ' Camb. Nat. Hist./ vol. ii, p. 333. 



5 ' Mem. Soc. nationale Sc. nat. et Mathem. Cherbourg/ t. xxi, pp. 101 — 186. 



6 ' L. M. B. C. Memoirs/ xi, Arenicola, 1904. 



7 ' Mitt. Zool. Mus. in Berlin/ Bd. iv, p. 148, 1910. 



