82 ZOOLOGY. 



This coral ranges as far north as Xantucket and Buzzard's 

 Bar. In the mushroom corals, Fungia, the large corallum 

 is the secretion of a single polyp which may be a foot in 

 length. Large branching corals abound on the reefs of 

 Florida, the most abundant of which grows nearly two feet 

 high and branches out like the horns of a deer. Such is 

 Madrepora cervicornis Lamarck. 



A\'hile agamogenesis or alternation of generations is rare 

 among the Actinozoa, Semper has observed two species of 

 Fungia which he considers to reproduce in this way. The 

 corals " bud out from a branched stem, and then become 

 ■detached and free, as is the habit of the genus." Moseiey 



rig. 64.— Coral polyp (Aslroulee calyadaria) espanded.— From Tenney's Zoology. 



•also describes a similar case of production of three or four 

 geueratiuus in a Tahitan species of Fimgia. 



As a good example of the mode of deTelopment of one of 

 the suljorder Madreporaria, we will, with Lacaze-Duthiers, 

 study the development of Astroides calycularif Pallas. 

 The period of reproduction takes place between the end of 

 May and July, the young developing most actively at the 

 end of June. Unlike Actinia, which is always hermaphro- 

 ditic, this coral is rarely so, but the polyps of difiEerent 

 branches belong to different sexes. 



As in the other polyps, including Actinia, the etrss and 



