144 Royal Society : — 



minating at the side of the oesophagus in a blind sac. The posterior 

 brachial canal probably communicates with the perivisceral cavity and 

 exhibits a peculiar arrangement of muscles, by whose action perhaps 

 the arm can be exserted. 



In addition to those parts of the alimentary canal and its append- 

 ages which are already known in the articulated Brachiopoda, the 

 author describes a short median gastro-parietal band arising from the 

 upper surface of the stomach and passing upwards and backwards to 

 the dorsal parietes a little in advance of the hinge-plate. With 

 regard to the existence or absence of an anal aperture in the articu- 

 lated Brachiopoda, the writer states : *' I have made numerous dis- 

 sections under a powerful doublet, and have removed the part and 

 examined it with a microscope : I have filled the tube with fluid 

 as the fingers of a glove with air, and by pressure have attempted to 

 force a passage : I have tried injections ; but have equally, on all 

 occasions, failed to discover an outlet, and have only succeeded in 

 demonstrating more and more clearly the ceecal nature of the ter- 

 minal extremity of the alimentary canal. Therefore, how much 

 soever it may be opposed to analogy and to authority, the fact must 

 be recorded — there is no anal orifice in Waldheimia^ Terebratulinay 

 or in Rhynchonella.^* 



In Lingula, as in the articulated Brachiopoda, the first inflection 

 of the intestine is towards the ventral surface, but the alimentary 

 canal eventually ends in the easily observable anus placed nearer the 

 dorsal than the ventral surface, on the right side of the body. The 

 rudimentary mesentery, and the lateral gastro-parietal and ilio-parietal 

 bands of Lingula are described. There is no median gastro-parietal 

 band. Faecal matter rolled into round pellets is commonly obser- 

 vable in the intestine of Lingula, while no faeces are ever found in 

 that of the articulated Brachiopoda. 



The genitalia in the articulate Brachiopoda are developed between 

 the two membranes of which the inner wall of the pallial sinuses in 

 which they are contained is composed, and, thrusting the inner of the 

 two membranes from the outer, form a prominent mass connected by 

 a band with the inferior wall of the sinus. The genital artery runs 

 along the upper or outer edge of the band, and the genitalia are 

 developed round it. 



In Lingula the reproductive organs are withdrawn from the man- 

 tle and lodged within the visceral chamber, forming four irregularly 

 lobulated or branched masses, two above and two below the alimen- 

 tary canal, so that they may be distinguished as dorsal and ventral 

 genital masses. The dorsal ovaries are suspended by the ilio-parietal 

 bands, and the ventral by the continuation of these bands along the 

 free margins of the pseudo-hearts. In both cases the attachment is 

 along the margins of the bands, which are related to the genitalia 

 much in the same manner as the suspending membrane is to the 

 genital bands in Waldheimia ; and it would seem that in Lingula 

 the reproductive organs are really developed between the two layers 

 composing the ilio-parietal bands. The author adduces arguments 

 to show that the Lingulce are hermaphrodite, the testis being a red- 

 dish mass, which ramifies over the true ovary. 



