54 F. A. SMITT, 



ridan Cellepora tuberosa, does not raise itself, secondarily, the whole avicularium beino- 

 enclosed in the secondary zooecial aperture; and the ocecia, in the same likeness, remain 

 more freely raised above the common secondary layer of calcification of the stem. The 

 great spathulate avicularia are common to all the three forms; but on the Cellepora 

 margaritacea alone we have seen bristles (marginal spines), four to the number, on 

 the primary margin of the zooecial aperture. As to the size of the zocecia, I have 

 measured the breadth of their primary aperture of Cellepora margaritacea, to be about 

 0,1 mm. 



For the systematical arrangement, in comparing the three last-named Cellepora?, 

 any difference of truly specifical value scarcely will be to find. They are, evidently, 

 three different varieties of size, of growing and of calcification, of the same type. The 

 smooth surface of the Cellepora margaritacea is produced by the continuous secondary 

 layer of calcification concealing the limits between the zocecia, which was to be seen, 

 also, on the Cellepora avicularis, although, in connexion with the difference in the form 

 of the stems, in a little differing manner of extension. The degree of raising the avi- 

 eularian rostrum at the zocecial aperture, in this group, is all too variable for giving 

 any available character. Still the three varieties seem to be very constant and may 

 very well deserve their own naraes. 



From the group, which here Ave have named Hippothoa, under the narne of 

 Escharella once x ) I have separated another group of Myriozoidan forms, characterized, 

 principally, in the constitution of the zocecia, with their front side, typically, more or 

 less plain and pierced by primary pores. The Myriozoidan character in the proceeding 

 calcification appeared, in the round or rounded-quadrangular primary aperture, by pro- 

 ducing a lateral denticle, on each side, at the articulation for the operculum and by 

 then filling up the proximal part of the aperture almost in the same manner as Hip- 

 pothoa, but retaining the median sinus more open, semicircular. In the proceeding 

 development, in connexion with the calcification, in the middle of the proximal margin 

 of the aperture, very often they produced a median denticle, and proximally of the 

 aperture very commonly they would develope a median avicularium, more or less inti- 

 mately connected with or enclosed in the secondary raising of the aperture. These 

 characters, it must be confessed, as a natural consequence of the variability of the spe- 

 cies in question, are very vague; and, indeed, the whole group is to be regarded as a 

 connecting link between the types of Hippothoa and Eschara. 



As the first example of a prototypical form of this group, as well as of the 

 difficulty of distinguishing it from the preceding genera, we may cite the 



Escharella sanguinea 2 ) (Pl. VIII, figs. 164 ancl 165). 



This species, in well-developed colonies, of a whitish hue, in free expansions as 



') Öfvers. Vet. Akad. Förh. 1867, Bih., pp. 8 and 70. 



-) (?) Escharina torquata, D'Oli]3., Voy. d. VAmér. mér., vol. V, part. 4, p. 11, tab. IV, figg. 1 — 4. 



(?) Cellepora subtorquata, Id., Pal. Franc, Terr. Crét., vol. V, p. 399. 



Ilemeschara sanguinea, Nohm., Quart. Journ. Micr. Se, n. ser., vol. VIII, p. 222, tab. VII, figg. 9 — 11. 



