NEW SPECIES OF PERICHiETA. 207 



thick. The gizzard, therefore, appears to belong almost entirely 

 to segment viii. (fig. 4 e), and scarcely enters the next segment. 

 Its relative size and extent, as well as the fact that there is a 

 normal proportion of oesophagus between it and the septum 

 x.,/xi., seem to indicate that the gizzard practically belongs to 

 one segment, not only in this species, but possibly in others, in 

 which it is variously stated to occupy segments viii. & ix., or virr.^ 

 IX. X., for the reason, chiefly, that there are no septa between 

 these segments and that it occupies nearly, but not quite, the 

 entire space between the septa yii./yiii. and x./xi. There is 

 nearly always a certain amount of oesophagus between the 

 gizzard and this hinder septum (x./xi.), which, in the various 

 species I have dissected, is much larger than it appears to be at 

 first sight. 



In his Monograph, Beddard gives as a character of the genus 

 the position of the gizzard in segments yiii., ix., the intervening 

 septum being absent. The fact that the gizzard does lie in the 

 8th segment in certain species is recorded by Beddard * in 

 P. Everetti, P. pentacystis, and P. hinabaluensis ; but the evi- 

 dence in support of this statement is not given, nor is the fact 

 emphasized, though similar evidence to that just given for the 

 present species is recorded for P. trityphla, Bedd. f. Moreover, 

 EosaJ regards the 8th segment as the normal morphological 

 position of the gizzard: he says, in his description of P. Udei: 

 "Ventriglio grande a tronco di cono, lungo quasi tre 

 segmenti ma anch' esso appartemente morfologicamente al 

 solo segmento 8° percio il setto rudimentale 8/9 e profonda- 

 mente infundibulato." 



Michaelsen also finds species in which the gizzard is confined 

 to segment viii. 



There is a simple and short intestinal caecum on each side, 

 arising in segment xxvii., and not extending beyond the pre- 

 ceding segment. 



The vascular system is rather instructive. The dorsal vessel, 

 after passing forward through septum x./xi., gives ofi" a small 

 "lateral heart," immediately in front of the septum {a, fig. 4 e) ; 

 in front of this another commissural vessel (b), not dilated, arises 

 from the dorsal vessel, just behind the gizzard, and presumably 



* Annals & Mag. Nat Hist. xvi. 1895, p. 69. 



t Proc. Zool. Soc. 1896, p. 205. 



I Ann. Mus. Civ. Stor. Nat. Genova, (2) xvi. 1896, p. 522. 



