Bihliographical Notice. 171 



deposited iu different zoological provinces, and corals then lived in 

 the Indian seas which are not found in Europe until later ; simi- 

 larly some European families, such as the Amphiastrajidic, which 

 are not represented in the Putchum limestones, appear to have 

 entered the Indian region, and become abundant there, during the 

 subsequent Chari period. , . . Among the European Bathonian and 

 Callovian faunas the Cutch corals most closely resemble those of 

 the Crimea and of Galicia described by Eichwald, Solomko, and 

 von lleuss. The most striking feature of the Cutch corals is the 

 prevalence of small patelliform corals and of rounded nodular ooralla 

 in the massive forms ; there is a marked absence of corals with the 

 arborescent growth so common in the European Jurassic species. 

 Even genera in which the coralla are typically caespitose, such as 

 Goaiocom and Latormcandra (sensu stricto), are represented in 

 Cutch by low nodular coralla. Encrusting corals are very scarce. 

 We may infer, from the predominant nodular form of the coralla, 

 that the corals grew on a loose sea-floor exposed to such strong 

 currents that arborescent and lamellar growth was impossible. 



" Hence, in spite of the great local abundance of corals in the 

 Upper Putchum beds, to the north-west of Jumara, it does not 

 appear correct to speak of the deposit as a coral-reef. A reef is a 

 line of rocks that reaches or nearly reaches to the surface of the 

 sea. The Jumara corals cannot have formed coral-rocks, and wo 

 may infer, from the rarity of rolled beach-worn specimens, that the 

 corals lived below the depth of surf-action. The Jumara deposit 

 may therefore be better described as a coral-bank than as a coral- 

 reef " (page 4 ). 



The nomenclature of the coral skeleton is carefully explained, and 

 an interesting account of the several classifications and revisions of 

 the Madreporarian corals is given, together with a necessary con- 

 sideration of the taxonic value of the skeletal structure. A very 

 useful bibliographic list is also given (pp. 23-27). 



The preliminary studies above suggested lead to a possible critical 

 determination of "Coral Species" (pp. 17-22). (1) There may be 

 mutations, changes, or variations in structure and form more or less 

 differentiated by peculiarities in the growth of the individual, either 

 hereditary or unique. (2) Extreme variability of form among the 

 Invertebrata and the common sorts of plants may be owing to con- 

 ditions of growth ruled by circumstances of environment, and it is 

 possible for two closely agreeing forms to be merely homoplastic, 

 but having no dehnite affinitj'. 



Thus certain corals may have " probably descended from different 

 types and have independently acquired the same specific form. To 

 give them the same specific name would therefore be misleading, as 

 it would imply a relationship that does not exist. 



" If we admit the possibility of the independent acquirement of 

 the same specific characters, it is clearly misleading to correlate 

 deposits by the presence of such ' species,' for the group of corals 

 inchidcd in a 'species' may be quite an artificial assemblage. 



