76 PROCEEDINGS OP THE AMERICAN ACADEMY 



PLATE III. 



Fig. 19. Profile of young specimen eleven days old. 

 „ 20. Head of same, seen from above. 

 „ 21. Magnified pectoral of same. 

 „ 22. End-view of sucking-disk of same. 

 „ 23. Profile of head of specimen somewhat more advanced. 

 „ 24. Profile of sucking-disk of another specimen about in the same stage of 



development. 

 „ 25. Tail of specimen of same age as fig. 19, but somewhat more advanced. 

 „ 26. Gill-opening of same, seen from above. 

 Figs. 27, 28. Profiles to show protuberances of sucking-disk of head in different 



degrees of expansion, one day older than preceding stage. 

 Fig. 29. Profile of head of specimen thirteen days old. 

 „ 30. Profile of young Lepidosteus 20 mm - long, nineteen days old. 

 „ 31. Head of same, seen from above. 

 „ 32. Tail of specimen seventeen days old, but evidently more advanced 



than the preceding figure (30). 

 „ 33. Head of same (fig. 32), seen in profile. The young specimen measured 

 20 um in length. 



PLATE IV. 



Fig. 34. Young Lepidosteus, twenty days old, slightly larger than the stage of 



the previous day, seen from above. 

 „ 35. Tail of same, seen in profile. 



„ 36. Profile of young, 21 mm in length, twenty-four days old. 

 „ 37. Head of same, seen from above. 

 „ 38. Young, seen in profile, twenty-five days old. 

 „ 38a. Profile of tail of same, showing commencement of fin-rays of caudal, 



anal, and dorsal fins. 

 „ 39. Natural attitude of young Lepidosteus, thirty days old, seen in profile, 



^f of an inch long. 

 „ 40. Tail of young Lepidosteus, thirty -eight days old, of about the same 



length as the specimen of fig. 39. 

 „ 40a. Pectoral of same. 

 „ 41. Profile of jaws of same. 

 „ 41a. Commencement of ventrals of same. 

 „ 42. Head of same, seen from above. 

 „ 43. Gills of same, in profile. 

 „ 44. Gills and gill-arches, seen from below. 



PLATE V. 



Natural attitude of young Lepidosteus (early part of July) after it has assumed 

 to a great measure the coloring of much older specimens. This specimen 

 measured about an inch in length. 



