492 A. Agassis — EcMnorieus Van Phels. 



horizontally, and finally in the Atelostomata the girdle and 

 jaws are completely absent. We may imagine the process of 

 resorption of the lantern of Echinoneus to have gone through 

 some such succession. 



EXPLANATION OF PLATE II. 



a, auricle ; an, anal system ; c, compass, 

 i', actinal loop of the alimentary canal. 

 i", abactinal loop of the alimentary canal. 

 ia, abactinal intestinal appendage. 



I, labium. 

 m, madreporic tube. 

 mc, muscular band leading to compass. 

 mo, actinostome. 



pm, pentagonal muscular band of summit of lantern. 

 py, pyramid. 

 t, tooth. 



1. Profile longitudinal section of young Echinoneus measuring 4 - 25 mm in 

 length. 



2. Transverse section of young, 3 - 70 mm in length and 2 - 55 mm in width, 

 showing the actinal floor, the position of the lantern, and of the actinostome 

 seen from the abactinal side. 



3. Lantern of Echinoneus magnified (l^O™ 111 in diam.) same as fig. 2. 



4. Actinal part of ambulacral system seen from the interior of young 

 4*19 mm in length to show the auricles. 



5. Pyramid and tooth seen from the exterior, length 0'85 mm . 



6. Pyramid and tooth seen from the interior, length 0'85 mm . 



7. Tooth seen in profile, length 0*62 mm . 



8. Compass seen from above, length 0"62 mm . 



9. Compass seen in profile, length 0'62 mm . 



10. Profile of young specimen measuring S^ 111111 in length ; the lantern and 

 auricles have disappeared. 



