Gattij Marine Lahoraforij, Si. Andrew!. 253 



translucent mass {coilc.) behind the diaphragm and on 

 each side of the gut. 



Myriochele, the second genus of the Ammocharidaj, differs 

 from Owenia in the simplicity of its anterior end, for it is 

 l)roadly truncated, with a smooth margin, a deep pit or 

 vestibule leading to the mouth, and a ventral fissure; yet it 

 is found that, thougli tiie branchiae aie absent, the nervous 

 system is formed much on tlie same plan as that of Owenia. 

 Myriochele is even more broadly truncate than Owenia, and 

 as a transparent object its large blood-vessels in front 

 and the great longitudinal mucous glands which follow 

 give the body a striped aspect. 



The cilia covering the large funnel-shaped oral cavity of 

 Myriochele are long and powerful, so that the currents they 

 cause are probably considerable. Moreover, the oral aperture 

 is oblique, the rim dipping backward to the notch at the 

 ventral border, thus somewhat resembling the condition in 

 the young of Oivenia^ though the oral gap is larger. 



In the early sections of the snout of Myriochele the 

 hypoderm presents more distinct elements than in Owenia, 

 and it appears to be somewhat thicker, its minute cells and 

 granules in the gelatinous matrix being conspicuous. The 

 sections have a horseshoe-sha|)ed appearance, the wide oral 

 gap beneath forming the heel of the shoe, Avhich, however, 

 is ta])ered at the tip, the wall thinning off at each side. The 

 exterior of the shoe has cuticle, glandular hypoderm, and 

 basement-tissue resting on a gelatinoid layer which has 

 numerous minute nucleated cells along both outer and 

 inner borders. Basement-tissue, again, bounds the vesti- 

 bular hypoderm on the inner border, which differs from that 

 of the outer wall in having a distinct inner coat, from which 

 cilia probably spring. The basement-layer in both cases 

 is apparently elastic. The surface-layer of hypoderm 

 often presents clear spaces or vacuoles — proliably from 

 rupture and extrusion of the glandular tissue. Moreover, 

 its external surface forms a more definite cuticle, whilst its 

 inner border rests on the basement-layer, no nervous belt 

 appearing in the first sections ; but circular fibres occur 

 within the basement-layer, and then a well-developed longi- 

 tudinal coat of muscle which stretches downward to the 

 oral edge, from which the epithelium of the mouth passes 

 inward (PI. XI. fig. 22) as a thick layer of cylindrical cells 

 with nuclei, bounded internally by a thin sheet of cii'cular 

 fibres and a few longitudinal strands. The space (coclom) 

 between the body-wall and the oral wall shows many 



