j I I " TERRA NOVA " EXPEDITION. 



demibranchs (Fig. 1-1, it/.c.), which terminates further back as a blind pocket between 

 the body-surface and the kidney. 



\Yithout further and more extensive inquiry it is hardly possible to judge 

 adrt|iiatelv of the importance of such structural details as these; but, so far as can 

 be seen with the material at hand, they are undoubtedly suggestive of an affinity 

 I iet \veen the animals concerned closer than that indicated by their shells, and thus lend 

 additional support to Pelseneer's view that Philobrya is in truth intimately related to 

 the An-idfi', and particularly to Adaenamt, although the shell is usually assigned to 

 another family of the Arcaeea. 



PECTINACEA. 

 PECTINID.E. 



G. Cliliimi/x consocictta, Smith. 



Station 96. A few specimens from 50 fathoms off North Cape, New Zealand. 



The anatomy of the animal is of the Pecten type ; although, owing to the presence 

 i >f a strong byssal apparatus, the musculature differs considerably from that of the 

 genus Pecfi'ii, and by its one-sided development throws the body more or less out ol 

 symmetry. 



Mn ii tic. The mantle is quite similar to that of Pecten, with a large inturued inner 

 fold or curtain, and numerous eyes of the Pert en type along its free border. 



Miixdcx mid Foot. The single adductor muscle consists of two distinct parts, 

 which are situated, when the hinge-line is placed to the left, one above the other. The 

 fibres of each part are diagonal to those of the other ; those of the upper part passing 

 forwards from right to left, and those of the lower forward from left to right. As in 

 Pecten, the fibres of the two parts differ in histological structure ; those of the lower part 

 being transversely striated, those of the upper smooth. The posterior pedal retractors 

 are represented by that of the left side only. This muscle is of great size, and passes 

 across the body behind the pericardium to the base of the byssal papilla, into which it 

 is inserted. 



The byssal papilla occupies a deep cleft in the ventral surface of the finger-shaped 

 foot, and as in Ami and Barhatia is broken up into a number of parallel longitudinal 

 laminae. 



Nervous tii/stem mid Sense-Organs. The central nervous system resembles that ol 

 I'ccf, //. particularly in the extreme condensation of the cerebral and pedal ganglia, these 

 being so closely applied to one another that they form a continuous horse-shoe shaped 

 mass without any outward indication of cerebro-pedal connectives or pedal commissure. 

 The cerebral ganglia are, as in Pecten, widely separated. 



The otocysts are large, and lie above the pedal ganglia, within the embrace of the 

 re re] iro-pedal mass. 



