Revieios — Professor G. Lindstrom on HelioUtidce. 273 



In the tribe Heliolitinee are comprised three genera : HeUolites, 

 Dana, with a ccenenchyma of tubes of one kind and size ; Cosmiolithus, 

 gen. nov., in which two different kinds are present ; and ProJieliolites^ 

 Kiser, with slightly developed ccenenchyma, with gemmation from 

 single tubes. The septal spines are bent downwards. 



The predominant genus, not only of the tribe, but of the whole 

 family, is HeUolites, Dana, and in this genus eleven species and 

 varieties are described, six of these being new forms. The very 

 thorough microscopic revision to which the various species of the 

 genus have been subjected by the author has involved, as might 

 have been anticipated, the suppression of some reputed species and 

 the transposition of others, and it may be that some of these changes 

 will not be accepted without protest. As an instance of a needful 

 alteration may be mentioned HeUolites (FistuUpora) decipiens, McCoy, 

 sp., hitherto regarded, even by Lindstrom, as a species, but now 

 proved to be only a phase or growth modification of H. inter stinctus, 

 L., and thus merely a variety of this latter. In the same specimen 

 there may be found some calicles with fully developed septa as in 

 H. inter stinctus, others without a trace of septa, as in H. decipiens, 

 and yet other calicles with the septa unequally developed. 



As incidental to the presumed affinity between the Heliolitidee 

 and such forms as Monticulipora, Callopora, and FistuUpora, now 

 very generally regarded as Polyzoa, the author enumerates sevea 

 chief differences in the structure of these groups, of which the most 

 important appears to be the dissimilarity of the intimate microscopical 

 structures composing their walls. 



In the tribe Plasmoporinse are included Plasmopora, M. Edw. and 

 Haime, Propora, M. E. & H., Camptolithus, gen. nov., distinguished 

 by having the same kind of vesicular tissue in the calicles as in the 

 ccenenchyma; and Diploepora, Quenstedt, in which there are two 

 kinds of ccenenchyma — an inner of vesicular character and an outer 

 of closely arranged parallel rods. The only species of this genus is 

 D. Grayi, M. E. & H., sp. The genus Lyellia, M. E. & H., is not 

 retained, on the ground of its similarity to Propora. 



As a special feature of Plasmopora, it is pointed out that the septa 

 extend beyond the calicular theca, and their ends are united together 

 by a curved lamina so as to form a stelliform area or aureola, 

 enclosing longitudinal compartments around the calicle. Thirteen 

 species are placed in the genus, ten of which are new forms. In 

 Propora the calicles are exsert, the. ccenenchyma entirely vesicular, 

 and there is no aureola. Nine species and varieties, including six 

 new forms, are described. The genus Pinacopora, Nichol. & Eth., 

 is considered to be a synonym of Propora. 



The only genus of the Pycnolithinse tribe is Pycnolithis, gen. nov., 

 in which the common type of calicle is accompanied by a dense, 

 compact ccenenchyma, without any structure, but with a surface 

 ornamented by shallow elongate grooves and pits. 



We are unwilling to conclude this notice without again repeating 

 our warm appreciation of the able manner in which the subject has 

 been treated by Professor Lindstrom, and our admiration of the 



DECADE IV. — VOL. VI. — NO. VI. 18 



