74 ZOOPHYTES. 



and every new branchlet, though at first nearly horizontal, soon be- 

 comes erect. The Madrepora prostrata, plate 33, figure 1, is a good 

 example of this process, as well as the other corals of the same plate, 

 and all the vase Madrepores. Were it not that the new budding-polyps 

 were developed on the outer side of the branches, the zoophyte would 

 at once lose its horizontal position. The branchlets in these species, 

 after becoming erect, are symmetrical in their mode of growth. The 

 formation of parent-polyps, on the outer side of the main branches, is 

 favoured by the more perfect exposure to the fresh ocean waters than 

 is enjoyed in any other part of the zoophyte. 



This mode of branching produces generally arborescent forms, and 

 is mostly confined to species budding from a parent-polyp. Yet the 

 Gorgonise, Seriatoporge, and Porites, afford examples of the same 

 result, from parent-clusters. The wart-like prominences over the 

 surface of a Pocillopora, may be produced by an analogous process. 

 As the budding-cluster of the apex enlarges by growth, and the older 

 polyps join those of the lateral surface, small clusters of two or 

 three in each, at nearly regular intervals, retain the budding power, 

 until these prominences have a certain length, usually not exceeding 

 two lines. 



Budding of a hrancli. 



75. Besides the budding of a single polyp, there are some species 

 which form a group at a single budding process. This fact is pointed 

 out by Milne Edwards, in his description of an Alcyoniura.* A knob 

 or protuberance swells out from the surface, which, on dissection, is 

 found to be penetrated by tubes branching and subdividing towards 

 the surface, and all proceeding from a common trunk, or a collection 

 of trunks, which branch from one or more, as the case may be, of the 

 old polyps. The young polyps were distinguishable at the extremi- 

 ties of the tubes before they made their appearance externally ; and 

 finally a cluster of animals was developed, and a new branch added 

 to the zoophyte. This process appears to be confined to this division 

 of the Actinoidea. 



II. Superior or Terminal Budding. 



76. While in lateral budding, increase, in the prolate growth of a 

 zoophyte, takes place from the extension of the lower part of the 

 polyps, in terminal budding it proceeds from the extension of the 

 summits. This process of widening in the budding-polyps may be 

 confined to the parts exterior to the disk and visceral cavity below, or 



* Ann. des Sci. Nat., 2d Sen, iv. (1835.) 



