98 ALDER, ON NEW BRITISH POLYZOA. 
CrLLEPORA CERVICORNIS, }leming. 
Much difference of opinion exists concerning the British 
species generally known under this name. The points in 
dispute are :— 
Ist. Is the species a Cellepora or an Eschara? 
2nd. Is it the same as the Eschera cervicornis of Milne 
Jdwards, and the Millepora cervicornis of Pallas? 
3rd. Are more than one species confounded by British 
authors under the name of Cellepora (or Eschara) cervicornis ; 
and does the species figured by Dr. Johnston belong to it? 
With respect to the first of these questions, it may be 
stated that, in its young state, and at the ends of the branches, 
this species has the character of an Eschara; the polyzoary 
being much compressed, with the cells arranged back to back, 
in regular quincunx. The form of the apertures is ovate or 
nearly circular, and a little contracted below, with a central 
avicularium on the lower lip. In a more advanced state the 
apertures become orbicular, and the basal portion is con- 
tracted into a narrow slit or sinus. As age advances, addi- 
tional layers are superimposed, giving the stem and branches 
amore rounded form, and on each layer the cells become 
more irregular, until they are confusedly scattered, heaped 
together, and raised at intervals. In this state the species 
assumes the character of a Cellepora. A different view of its 
generic position may therefore arise, according as its older or 
younger portions are taken for illustration. Admitting its 
adult state to be the perfect form, I agree with M. Milne 
Edwards in considering the species to belong to Cellepora 
rather than to Eschara.* 
On the second point I am also inclined to agree with M. 
Milne Edwards in the opinion expressed below. The E. cervi- 
cornis, so well described and figured by that able naturalist 
in his ‘ Recherches sur les Eschares,’ is more slender in form 
and less expanded at the top of the branches than in the 
British species. The cells in the young part are more pro- 
minent, and the apertures more elongated. But the chief 
difference is in the older part of the stem and branches, which 
* “M. Fleming a décrit aussi sous le nom de Cellepora cervicornis 
(‘British Animals,’ p. 532) un Polypier qwil a trouvé sur les cétes de 
Ecosse, et qu’il considére comme identique avec le Porus cervinus dIm- 
perato, etc.; mais d’aprés linspection d’un écbantillon qu il a envoyé sous 
ce nom au Musée de York, nous ne doutons pas que ce ne soit une espece 
tout-a-fait distincte, et méme un yéritable Cellepore plutot qu'un Eschare.” 
—Recherches sur les Eschares. 
