190 SUMMARY OF CURRENT RESEARCHES RELATING TO 



iu the cceloBi, but are confined to the segments in which they are 

 developed. The spermatozoa are developed iu great quantities, and 

 are, when ripe, excessively active ; they resemble in form those of 

 Magelona. 



As efferent ducts for the products, we have the so-called segmental 

 organs ; they differ somewhat from those of other Chaetopods, being 

 tubular structures, in which it is not possible to distinguish different 

 regions; the whole is very short, and only just extends into the 

 coelom • the external and internal orifices are somewhat widened out, 

 but are not specially differentiated. They are not developed in the 

 anterior portion of the body, where their place appears to be taken 

 by a coil of cells with distinct nuclei ; these are regarded as glandular 

 orc^ans, but no efferent ducts can be detected, and their development 

 must be studied before their homologies can be exactly defined. The 

 body easily breaks, and regeneration was found by experiment to be 

 somewhat complete, 22 segments appearing where 42 had been before, 

 20 where there had been 33, 26 for 40, 27 for 63, and 24 for 68. 



Parasitic Eunicid.* — Dr. J. W. Spengel, in describing Oligo- 

 gnathus Bonelliae, remarks that parasitic Polychaeta would seem to 

 be very rare, the young Alciopids which are parasitic in Ctenophora 

 affording the only other real exception to the rule that the Polychfeta 

 lead a free life. On examining some Bonelike at Naples, the author 

 found in their coelom an orange-coloured cord which attracted his 

 attention by its lively movements. Not more than 10 cm. long, 

 with a thickness of 1 mm. in its middle, it had more than 200 

 segments, together with a region of incomplete segmentation. The 

 maxillary apparatus was rudimentary, and there were only three small 

 teeth on the upper jaw. In the observations which follow his 

 systematic account, the author enters into some comparison of the 

 characters presented by this new form with those which are to be 

 seen in some of its allies. 



In dealing with its nervous system, the author points out that, 

 while the oesophageal commissure contains but few ganglion-cells, 

 there is a well-marked sub-oesophageal ganglion in the second 

 segment ; in the next six or seven, there are, as in it, two ganglia ; 

 further back, the swellings are inconsiderable ; the elements of the 

 ventral cord are arranged in typical fashion, save that the fibres form 

 not two but three connecting cords. When compared with its allies, 

 it is shown to be remarkable by the possession of a secondary ganglion 

 in each segment, by the great breadth of its anterior ganglia, and 

 by the close connection between the ganglia and the epidermis. In 

 it the ganglia are all subequal, but in Holla the anterior ganglia 

 contain a few giant-cells, each of which is provided with a special 

 thick investment, formed of concentric fibrous layers with numerous 

 spindle-shaped nuclei. The tubular sheaths thus formed are com- 

 parable to the " fibres tubulaires gigantesques " long since described 

 by Claparede. After discussing the arrangements found in other 

 formSj the author concludes that it must still remain uncertain 



* MT. Zool. Stat. Neapd, iii. (1881) pp. 15-52 (3 pis.). 



