300 Prof. M'ltitosh's Notes from the 



This is one of the interesting additions made by Sontliern 

 on the south-western shores of Ireland. Tlie structure 

 generally is that of a Hesionid, but its special featur s 

 consist in the peculiar lyre-shaped dorsal bristle and the 

 hood-like extension of the pygidium. Mecznikow's original 

 description is diagnostic, and he mentions that he found a 

 female with eggs in segments 13 to 24. 



In the family of the Syllid.e, Caullery and Mesnil * pro- 

 pose to institute a new genus, viz., Parexogone, for the 

 Pcedophylax hebes of Webster and Benedict, which Southern 

 has procured on the west coast of Ireland, the head being 

 formed into a sort of cone with fused palps. The anterior 

 region of the alimentary canal is muscular, with proboscis, 

 crop, and gizzard. The cuticle is thick. The animals fre- 

 quent compact sand, and the habit for Syllids is thus peculiar. 

 Moreover, an important paper on the group, with excellent 

 illustrations, has recently been published by Prof. Haswellf, 

 in which both systematic and structural features, as well as 

 developmental investigations, are detailed. Amongst other 

 interesting structural points he found that in some the 

 nephridia of each pair unite com|)letely at sexual maturity. 

 In Exogone fustifera the extrudid egg becomes a tached by 

 one end to the area on which the ducts of the pedal gland 

 open — internal to the ventral cirrus. He point* out that in 

 Exogone fustifera the formation of the coelom differs from 

 that of the Polychseta generally, since the stoniodseum ends 

 behind a mass of tissue (syncytium) in which the large yolk- 

 granules are embedded. The changes in this take place 

 before the young annelids become free. 



In Parexogone hebts, var. hibernica, Southern, the head 

 is separated from the palpi and buccal segment by faint 

 grooves, and the length exceeds the width. Three tentacles 

 — a long subulate median and two small laterals, which are 

 about one-fifth as long as the median. Three pairs of eyes 

 outside the lateral tentacles, and they vary in size ; exterior 

 to them are conspicuous, ciliated, nuchal organs. Palpi 

 large and fused dorsally, a shallow groove between them 

 ventrally. Brain elongated and bilobed. Buccal segment 

 as large as the head, bearing a pair of small bulbous ten- 

 tacles with stiff cilia at the tip. The body is about 7 mm. 

 long, with thirty-one bristled segments, somewhat fusiform, 

 creamy white in colour, without other pigment. The pro- 

 boscis extends from the second to the fifth bristled segment, 



* Bull. Soc. Zool. France, xlii. p. 127, 5 figs. (1918). __ 

 t Joui-n. Linn. Soc. vol. xxxiv. p. 217, pis. xvii., xviii. 



