52 BULLETIN : MUSEUM OF COMPAKATIVE ZOOLOGY. 



EXPLANATION OF PLATES. 



All the figures are camera drawings of specimens preserved and dehydrated in 

 alcohol and cleared in clove oil. 



PLATE 1. 



Fig. 1. Eight side of the anterior end of Branchiostoma pelagicum Giinther. 



X 30. 

 Fig. 2. Right side of the posterior end of Branchiostoma pelagicum Giinther. X 30. 

 Fig. 3. Left side of the posterior end of Asyrametron lucayanum Andrews, from 



tlie West Indies. X 40. 

 Fig. 4. Left side of the posterior end of Asymmetron orientale, sp. nov. X 25. 



PLATE 2. 



Fig. 5. Ileteropleuron agassizii, sp. nov. ; right side. X 5. 



Fig. 6. Hcteropleuron parvum, sp. nov. ; riglit side. X 12. 



Fig. 7. Asymmetron macricaudatum, sp. nov. ; right side. X 10. 



