MOLLUSCA. 191 



sinuses, situated close, and two strong tendinous membranes, 

 which circumscribe the visceral mass, and to which the 

 mantle-lobes firmly adhere. Here the veins of both man- 

 tle-lobes join, and the common trunk or sinus passes oblique- 

 ly through the membrane, and may be plainly seen distri- 

 buting ramuli over the liver and ovary. 



The muscles and viscera form a rounded mass, situated 

 in the posterior half of the shell. The mouth is seated be- 

 tween the base of the arms. The oesophagus passes ob- 

 liquely through the tendinous wall of the viscera in a direc- 

 tion towards the upper valve : it becomes slightly dilated, 

 and is then surrounded by the liver. The intestine is con- 

 tinued straight to the opposite end of the visceral cavity, is 

 there again contracted, makes a sudden bend upon itself, 

 and returns to the middle of the right side of the visceral 

 belt, which it perforates obliquely* and terminates between 

 the lobes of the mantle a little below the bend of the arms. 

 The liver is of a beautiful green colour, and consists of a 

 congeries of elongated follicles, closely compacted together, 

 which communicate by numerous orifices with the stomach, 

 As in Terebratula, there is no salivary gland. 



In Lingula Audebardii, Brod., there is also no salivary 

 gland ; and Mr. Owen is therefore disposed to believe, that 

 the gland described as such in Lingula anatina by Cuvier, 

 was only a portion of the liver, from which the colour had 

 probably been removed by long maceration in spirit. 



In the want of salivary glands the Brachiopoda would 

 seem to agree with the ordinary Bivalves. Destitute, like 

 them, of any hard parts about the mouth for comminuting 

 alimentary substances, glands for pouring in a fluid to 

 blend with the food during that operation, are not wanted. 



The nervous system in Terebratula was not detected by 



