432 ZOOPHYTES. 



Patrio-ramose ; arborescent, cespitose, or through coalescence, reticu- 

 late or foliaceous. Coralla with the branches terete (very rarely 

 compressed) ; calicles regular. 



Madrepore corals are the most common species in collections, and 

 are generally distinguished by their cylindrical branching forms, 

 covered with small calicles, each of which contains a minute cell. 

 The forms of the calicles are quite various. The principal are as 

 follows (see plate 31) : 



1. TuUform. Cylindrical in shape (figures 2 a, 3 a). The apex 

 may be either transverse (figs. 3 a), or oblique (figs. 35, 11 c, 12 b, 



c, d), and when oblique the aperture is usually oblong. They may 

 also be spreading, or close appressed to the branch (figs. 3 a, 9 a, 8 a). 



2. Nariform. A compressed calicle, resembling in shape a nose 

 inverted (fig. 4 a). It is triangular in profile, with the upper side, 

 which contains the aperture, nearly at right angles with the stem. 

 In some instances the outer lip of the calicle is elongate, producing a 

 rostrato-nariform shape ; and in others the nariform calicle is tubular 



.at base tubo-nariform (fig. 5 a, 45). 



3. Cochkariform. A short, stout, erect, cylindrical calicle, with a 

 broad apex, and the upper side partly wanting (fig. 10 a, 10 b). 



4. Dimidiate. A tubular calicle bisected vertically nearly to its 

 base (fig. 7 a). 



Labellate (from labellum, the lower lip}. Long-lipped, or in shape 

 nearly like the blade of a shovel, the upper side of the calicle being 

 entirely wanting, and the lower thin and nearly flat (fig. 6 a, 6 b, 6 c). 

 It passes into the dimidiate form. 



The cells are internally more or less perfectly radiated with minute 

 teeth. Of the twelve lamellae to which the teeth belong, half are often 

 smaller, or quite obsolete; sometimes only two opposite, the inner and 

 outer, can be distinguished, and of these the outer is usually largest: 

 these last occasionally meet and bisect the cell vertically. Figures 25, 

 3 c, 4c, and others on plate 31, represent some of the varieties. 



The most important characters for distinguishing species are as 

 follows : 



1. The mode of growth : a, erect, arborescent, stems solitary ; b, erect, 

 arborescent, and clustered (fruticose}; c, spreading obliquely upward,, 

 and much ramose, forming an even top clump (corymbed or fastigiate) ; 



d, spreading nearly horizontally, and often from a pedicel, with the 

 branchlets above nearly simple, digitiform, or spiciform, and forming 



