272 CAPITELLHLE. 



neuroglia between them. At the ganglia the cells of the neuroglia are increased and 

 surround the sides and ventral curve of the large ganglionic area as a deeply stained 

 chapelet. Moreover, the neural canal becomes indistinct. The perivisceral chamber is 

 crowded with minute nucleated bodies— the blood-corpuscles which Ray Lankester 1 found 

 to contain haemoglobin. 



Grube (1851) associated Oapitella with the Oligochaeta, placing it between Glitellio 

 and Nats, the type being the Lumhricus eapitatus of 0. Fabricius. 



The Capitellidae were placed by De Quatrefages (1865) amongst the sedentary 

 annelids between the Maldanidae (his Clymeniens) and the Arenicolidae, as a group of 

 uncertain position. His three genera were Oapitella, Notomastus, and Dasy bran elms. 

 This author's genera Areata and Ancistria seem to be connected with the Capitellidae, and 

 it is possible that imperfections in description may be the cause of their separation. 



Claparede (1873) observes that with regard to Notomastus and Oapitella, the one has 

 and the other has not the neural canals (his tubular fibres). He found these fibres in the 

 Serpulids and Spionids, rudiments of them in the Terebellids and Cirratulids, but absent in 

 the other families. 



The Capitellidae were associated by Levinsen (1883), after De Quatrefages, with the 

 Maldanidae under the Maldaniformia, yet this rested more on external aspect than on a full 

 consideration of other features. 



In (1884) Fischer 2 wrote his inaugural dissertation on the structure of Oapitella and 

 he gave an interesting but brief account of the various parts. He did not observe a neural 

 canal, and the figure of the hook is abnormal. 



Dr. Hugo Eisig published in 1887 3 a monumental work on the Capitellidae of Naples, 

 in which their structure, physiology, distribution, and systematic position were exhaus- 

 tively treated in text and plates. He gives an historical account of the members of the 

 family since Olafsen in 1774 described Oapitella capitata or Lumhricus littoralis minor 

 from Iceland. He divides the body into two regions, the thorax and the abdomen, and 

 gives a minute description of the anatomy of each group, taking Notomastus as the type. 

 In the body- wall of this genus, of which he has a diagrammatic transverse section, 4 he 

 indicates the usual structure from without inward in the abdominal region, characterising 

 the dorsal hooks as pertaining to the haemal parapodium, and the ventral hooks as 

 representing the neural parapodium. He terms the oblique muscles the transverse 

 muscles, and has an upper and a lower alimentary canal. External to the haemal para- 

 podium is the ciliated abdominal side-organ on the surface, whilst in the lateral region 

 is the parapodial branchial cavity. The alimentary canal is slung from the mid-dorsal 

 region by a mesentery, and the lower division is fixed to the transverse mesentery 

 over the nerve-cords. He deals with the alimentary canal under the heads of the proboscis, 

 gullet, chief gut and accessory gut, the two latter lying in the abdominal region. 

 Gregarinae occurred in the canal. Under the nervous system he describes spinal nerves 



1 ' Proc. Roy. Soc.,' No. 142, 1873. 



2 ' Anat.-Histol. Untersuch. von Oapitella capitata/ mit 2 Taf., Marburg, 1884. 



3 c Monographie der Capitelliden des Golfes von Neapel/ pp. 906, 37 plates and 20 text-figures. 

 Berlin, 1887. 



4 Op. cit., p. 17. 



