644 SUMMARY OF CURRENT RESEARCHES RELATING TO 



vasa deferentia open on to segment 12 ; the oviducts on to segment 13. 

 The spermathecse are in segments 4 and 5 ; each is furnished with a 

 pair of diverticula. During sexual maturity the spermathecas com- 

 municate with the lumen of the intestine ; in the neighbourhood of 

 the spermathecal apertures are peculiar aggregations of cells con- 

 nected with nerves and apparently sensory ; the buccal cavity contains 

 a projecting process of the mucous membrane, similar to what has 

 been described by Vejdovsky in Anachceta hohemica ; it appears, how- 

 ever not to be a gustatory organ but a sucker. 



Nervous System of Polychsetous Annelids.* — M. G. Pruvot finds 

 that the nervous system of Annelids is always, even when it is more 

 deeply situated, continuous with the hypodermis by at least part of 

 the surface of its ganglia ; it is always composed of a cortical sub- 

 stance which encloses nerve-cells in a stroma of anastomosing fibres, 

 and of a medullary substance which consists of peripheral nerve-cells 

 in a central dotted substance ; this last is to be regarded as the true 

 centre, and all the nerves really arise from it. The medullary sub- 

 stance forms four longitudinal trunks in the ventral chain, and of 

 these the two external do not communicate directly with one another, 

 but only with the two internal. 



The ganglia which are sometimes found on the oesophageal con- 

 nectives are only the first ventral ganglia which have ascended, and 

 have lost their transverse commissure. The stomatogastric has some- 

 times a double (cerebral and sub-oesophageal), sometimes only sub- 

 cesophageal or a cerebral origin ; when well developed it may, as in 

 the Euniceidee, reveal the characters of the general nervous system, 

 by forming a small ventral ganglionic chain, and an oesophageal collar ; 

 or, as in the Nepthydege and Phyllodoceidge its elongated roots may 

 terminate in a small peri-proboscideal ring formed by a large number 

 of small similar ganglia. 



In each segment the pedal nerve arises from the two ventral cords 

 by two roots ; it follows the integument for the whole of its course, 

 and divides into two branches, which again divide into two trunks 

 for the setigerous bulb and the pedal cirrus. All the appendages of 

 the somites are to be regarded as more or less modified feet ; the author 

 points out the differences which are to be found in different appendages 

 of various parts of the antennae, especially with regard to their 

 nervous supply. As the investigation of this necessitates the destruc- 

 tion of the animal, he points out that palpi may always be dis- 

 tinguished from antennaB by their insertion in the ventral surface of 

 the body, and by their form or size. 



Larval forms of Spirorbis borealis.f — Mr. J. W. Fewkes gives a 

 detailed description of the larval forms of Spirorhis horealis Dandin. 



The ova are in bead-like strings, composed of from one to four 

 rows with ten to fifteen or more eggs each. The later stages in the 

 segmentation of the egg resemble those of other chsetopod eggs : the 

 younger stages were not found. 



* Arch. Zool. Exper. et Gen., iii. (1885) pp. 211-336 (6 pis.). 

 t Amer. Natural., xix. (1885) pp. 247-57 (2 pis.). 



