220 THE ANNELIDA POLYCHAETA. 



di\'isioii the number may be as high as ninety-five, giving a maximum total 

 number of somites of about one hundred and ten. 



The prostomium as a whole is very elongate and is much longer than wide 

 (about in the ratio of seven to four) . It presents two sharply defined divisions, 

 a somewhat broader, more opaque, posterior division bearing the eyes, and in 

 front of this a translucent area which is rounded anteriorly, is flattened dorso- 

 ventrally, and on its ventral surface bears the tentacles. The preocular division 

 is scarcely more than two thirds as long as the posterior. Of the four eyes the 

 anterior pair are greatly larger than the posterior; they are nearly wholly 

 ventral in position, and are ventrally but narrowly separated. The lenses are 

 directed ectoventrad. The posterior eyes are dorsal in position, each occupying 

 an extreme ectocaudal corner of the prostomium. They are broadly elliptic 

 in outline as seen from above and the anterior end of each extends a little over 

 the posterior region of the corresponding anterior eye. The tentacles are 

 attached on the ventral surface a little caudad of the ventral border. They are 

 contiguous at base, short and conical in form, and usually extend either ventrad 

 or, more commonly, directly caudad, lying against the prostomium and reaching 

 about half the distance from the point of attachment to the basal division of 

 the prostomium. The palpi are very peculiar. In each the proximal joint is 

 fixed along one side to the ventral surface of the prostomium, its distal end lying 

 a little caudad of the posterior edge of the anterior eyes, from where the joint 

 reaches forward between the eyes, narrowing conspicuously forward and merging 

 with the prostomium before reaching the level of the anterior edge of the eyes. 

 The distal joint extends directly caudad over the border of the mouth. It is 

 conspicuously wider than the proximal joint, is well rounded, and but slightly 

 longer than broad. (Plate 31, fig. 2). 



Dorsally the peristomium is produced forward over the prostomium mesally 

 in the form of a conspicuous, usually very acutely tipped, triangular flap beneath 

 which the prostomium is correspondingly depressed. On each side of this the 

 dorsal eye projects back to the second somite over the peristomium. On the 

 ventral side the peristomium is much longer, not fully as long as a ventral eye. 

 The border of the mouth is broad and elevated and is strongly finely radially 

 wrinkled as usual. There are the usual four pairs of tentacular cirri. The ven- 

 tral cirri of the anterior pair are attached on the ventral surface between the 

 anteroectal border of the mouth and the corresponding eye on each side. Each 

 narrows to a slender acute tip and reaches caudad to the fifth somite. The 

 dorsal cirrus of the anterior pair is attached just ectad of the base of the ventral 



