19. The brains of vertebrates form at the ____ end of the nerve cord.

78. Which class of the superclass Gnathostomata is characterized by cartilaginous skeletons?

86. Sharks, rays, skates, sawfishes, and chimeras are members of the class ____.

Matching #3: Identify the indicated structures. Rat.jpg

79. Sea cucumbers can eviscerate and regenerate organs associated with the ____ system(s).

56. A medusa is often described as ____.

69. The word Porifera comes from a Latin word that means ____.

87. Which of the following is a membrane important in reptilian egg development?

67. A pearl is made from what natural process?

61. The primary function of microvilli is to ___.