MOLLUSCA : BRACHIOPODA. 



391 



the middle line, or else terminates in a distinct anus between 

 the pallial lobes " (Huxley). 



Within the pallial lobes there is a remarkable system of 



Fig. 204. Terebratula(Waldheimid)jlavescens. A, The shell viewed from behind, 



the beak, through which the muscular stalk of attachment passes. D, Longitudinal 

 and vertical section of the animal, showing the spiral arms (a), the stomach (s), and 

 the liver (ft). At /"is the opening in the beak, with the stalk of attachment (/) pass- 

 ing through it. (After Davidson and Owen.) Some details have been omitted in 

 figs. B, C, and D, for the sake of clearness. 



more or less branched excretory tubes, anastomosing with one 

 another, and ending in caecal extremities. This, which has 

 been termed by Huxley the "atrial system," communicates 

 with the perivisceral cavity by means of two or four organs 

 which are called " pseudo-hearts," and which were at one time 

 supposed to be true hearts, but which are now known to be 

 connected with reproduction. 



"Each pseudo-heart is divided into a narrow, elongated, external por- 

 tion (the so-called ' ventricle '), which communicates, as Dr Hancock has 

 proved, by a small apical aperture, with the pallial cavity ; and a broad, 

 funnel-shaped, inner division (the so-called ' auricle ') communicating, on 

 the one hand, by a constricted neck, with the so-called 'ventricle ;' and, 

 on the other, by a wide patent mouth, with a chamber which occupies most 



