AFFINITIES AND ZOOLOGICAI POSITION 65 



ous minute rays — affording thus another curious, false resem- 

 blance to a true coral." With this exception, nothing which 

 could be compared with the "septa" ^ of the Coelenterata has, 

 until lately (so far as I am aware), been noticed as occurring 

 in Heteropora. 



The above are the most important structural features which 

 had been brought to light by the study of the fossil species of 

 Heteropora ; but our knowledge of the anatomy of the genus 

 has been greatly extended by the investigation of recent 

 species by Mr Waters and Professor Busk, as already referred 

 to. The leading additional character which has been thus 

 brought to light is that the walls of the zooecia and cancelli (in 

 the outer portion of their course) are perforated by numerous 

 canals, which open into the cavities of the tubes by well- 

 defined circular openings, thus placing contiguous tubes in 

 direct communication. 



Having now shortly passed in review some of the more 

 important characters of Heteropora, so far as our present 

 inquiry is concerned, I may next give a short account of the 

 general features of H. neozelaniea, Busk, before describing in 

 greater detail its minute internal structure. The zoarium of 

 this species (fig. 8, a) is " erect, composed of short divergent 

 branches springing from a short thick stem, and soon divid- 

 ing once or twice dichotomously, and terminating in blunt 

 rounded extremities. The diameter of the primary branches 

 is .2 inch, and of the terminal ones about .1 to .15 inch. The 

 surface presents orifices " (see fig. 8, b and c) " of two kinds, 

 though scarcely distinguishable in size. The larger ones, in 

 the older parts of growth, have a slightly raised peristome and 



^ Professor Busk, in his descriptions of the species of Heteropora, frequently 

 employs the term "septa" to indicate the transverse plates which intersect the 

 tubes of certain forms of the genus. Mr Waters has followed Professor Busk in 

 this, or has sometimes employed the term "dissepiments" for the same structures. 

 It need hardly be pointed out that these terms have such a totally different signifi- 

 cance among the Coelenterata, that their use in this connection is undesirable, and 

 is apt to lead to confusion. The term ''septa," in fact, should be in all cases con- 

 fined to the radiating and vertical elements of a calcareous skeleton ; and the 

 plates so named in Heteropora axe. the analogues of the '' iabitlo'" oi the Coelen- 

 lerates. 



