ANATo.MY d|' I'KLKCYI'ohA liUIINK. i!.'!'.' 



Nervous System /unl .SV//.M - (>/-</<ni*. The nervous >vstem is similar to that of 



v, but tlic otocysts arc smaller and lie closer in the sides of the pedal ivinglin. 

 A cephalic eye is present in tin- usual position at the junction of the inner labial 

 palp and inner demibrancL The eye was litlle more than a pigment -fleck in one 

 instance (Fig. 8, <:,.). but in another specimen was a well-formed pigmented cup 

 occupied by a mass of hyaline material, larger and better formed than the cephalic 

 eye of .Lixxitrrii shown in Fi^. 4. 



niiji'xtiri' (h-ijuiifi ninl /////. The labial caeca and snli-liranchial epithelial ridge 

 mentioned in the description of l/i.^nrn are present, the latter being peculiarly well 

 developed and deep (Fig. '.).\, i;. C, <'/'./.}. 



The rectum, though not actually perforating the ventricle of the heart, is embedded 

 in the tissues of its ventral walls. The auricles, unlike, those of f/i*xnr<-<i, unite freely 

 behind the ventricle below the rectum. They show no development of pericardia! 

 gland-tissue. 



O'///.v. As mentioned above, the filaments of each deniibram-h are reflected and 

 not. as was the case in Pelseneer's specimens, those of the outer one onlv. This was 

 observed in whole preparations of the gills of three individuals from Stations :116, 338, 

 339 ; and in each case the condition was perfectly plain and open to no doubt (Fig. KA). 

 Towards the hinder end of both demibranchs, but especially of the inner, the reflexion 

 of the filaments becomes gradually less and less, some fifteen filaments of the inner 

 demibranch being simply direct. 



In the specimens used for sections reflexion of the inner demibranch seemed to 

 extend only about as far back as the middle of the body, but as sections vertical to 

 the body cut the gills very obliquely, this is the appearance that would naturally be 

 presented, bearing in mind that the. posterior fourth or so of the filaments are in fact 

 direct. 



The forward extension of the two demibranchs is similar to that of Lix*<ir<'tt. and 

 as in that genus and in Philobrya the anterior filament of the inner demibranch is 

 swollen and without reflexion. In the details of their structure the gills bear a strong 

 likeness to those of Philobrya (see below). The individual filaments are longer and 

 more slender than those of Lissarca, ami are united in both descending and ascending 

 arms bv ciliated discs situated about half-way down the lamina. Thev are also in 

 ciliarv union at their free ends and at the angle of reflexion. The reflected free end of 

 each terminates in a pronounced hook. The cavity of each filament is divided by a 

 longitudinal septum. 



In both Llxxiirrii and Adacnarca, the outer demibranch as it passes forward 

 separates from the inner demibranch and shifts its attachment more or less from the 

 bodv to the mantle. 



In Lixxiirrti this divergence is very slight, but in .\ilin-ntircn is of considerable 

 extent (Fig- 9A, ".'/., I.d.). The portion of the mantle-cavity included between the 

 forward ends of the demibranchs extends upwards beyond the attachments of the gills 



