NOTES ON HISTOLOGY OF LINGULA ANATINA. 21 



the supporting substance attains a considerable thickness pro- 

 jecting for a short distance posteriorly (PI. II., Fig. 24). To 

 this protuberance small bundle of muscle secures its attachment. 

 The muscle has a sheath of cell layer as in other muscles. It 

 runs ventral to the heart vessel, and posteriorly gradually at- 

 tenuating into a fine string, is finally inserted on the dorsal wall 

 of the stomach. The muscle serves probably to draw the posterior 

 part of the stomach nearer the region of the gastroparietal band, 

 facilitating the movement of food particles in the alimentary 

 canal, and indirectly of the lymph fluid in in the heart tube. 



V. OVARY AND TESTIS. 



On the sexual organs and elements of Lingula Blochmann 

 did not touch at any place in his recent paper ('oo). It may, 

 therefore, not be superfluous to devote a few pages to this point. 

 As for finer studies on ovogenesis and spermatogenesis I shall 

 put them off for some future time. 



IAngula is an animal of distinct sexes as is the case with 

 other Brachiopods. Morse was the first to emphasize this fact, 

 for he was able to study Lingula in life (73 b, p. 38). Thirteen 

 years later Beyer ('86), advanced another view, maintaining 

 that Lingula is hermaphrodite. This conception originates from 

 Hancock's statements. As both the sexual elements are very much 

 alike in appearance, the last named author did not distinguish the 

 testis from the ovary ; or, if not, the specimens he studied were 

 all female. At any rate he did not notice the true testis in his 

 monograph ('59) and regarded the dendritic proliferating zone 

 of the spindle bodies on the walls of the body cavity as the 

 testis. Beyer found the same structure as Hancock's supposed 



