AFFINITIES AND ZOOLOGICAL POSITION. 75 



lamellae, are known to exist in any species of Monticulipora. 

 In some species oi Heteropora, on the other hand, the tubes, in 

 the peripheral part of their course, are intersected by numer- 

 ous delicate spinules, which are arranged in a radiating man- 

 ner, and reach a considerable distance into the body-chamber 

 (sometimes nearly to its centre). These spinules in form and 

 arrangement precisely resemble the " septal spines " of many 

 species of Favositcs ; but, admitting the Polyzoan affinities of 

 Heteropora, it is obvious that they cannot be compared homo- 

 logically with the septa of any Coelenterate. 



(5) Transverse partitions, or " tabulae," are universally de- 

 veloped in the corallites of Moutictilipora ; and it is very 

 common for the different kinds of tubes which make up the 

 corallum to show marked differences in the nature and degree 

 of their tabulation. In Heteropora ncozclanica, Busk, tabulae 

 are, so far as I have seen, always present, though their 

 number is comparatively small. They are also undoubtedly 

 present in other species, and in greater numbers {e.g., in //. 

 conifera, Haime, and H. pustttlosa, Haime). So far as H. 

 neozelanica is concerned, the tabular seem to be confined to 

 the axial region of the corallites, and not to be developed in 

 the interstitial tubes at all, thus difterincr in both of these 

 respects from the tabulae of MofUiailipora. As in the case of 

 the radiating spines, however, just noticed, if we concede the 

 Polyzoan affinities of Heteropora, then the transverse parti- 

 tions which cross its tubes must have a different value and 

 import from the " tabulae " of Favositcs and of the so-called 

 " Tabulate Corals " in Qreneral. 



(6) Lastly, as to the supposed relationship between Mon- 

 ticiUipora and Heteropora, and as to the deduction which has 

 been drawn from this as to the propriety of referring the 

 former genus to the Polyzoa, it is clear that the points of like- 

 ness between the two are by no means so weighty as the 

 points of difference. On the one hand, we have a strong ex- 

 ternal resemblance, a general similarity in the mode of con- 

 struction of the skeleton, and an agreement in the fact that 



