353 



THE MONTICULIPOROIDS. 



Since " coenenchymal gemmation " is at present only known as 

 occurring (apart from the present family) in the unquestionably 

 Actinozoan groups of the Helioporidce and Heliolitidce, it would 

 seem that the presence of this mode of increase in the Fistuliporoids, 



first pointed out by Waagen, 

 is an almost incontrovertible 

 proof that the latter should 

 be referred to the Alcyonar- 

 ian Zoophytes. If this be 

 admitted, however, it would 

 follow, almost inevitably, 

 that the MonticuliporidcB 

 should also be regarded as 

 Alcyonarians, since there 

 exists an exceedingly close 

 relationship between these 

 and the Fistuliporoids. No 

 arrangement, in fact, which 

 would refer Fistulipora and 

 Callopora to one great di- 

 vision of the animal kingdom (Cceknterata), and would place Mon- 

 ticulipora, Diplotrypa, and allied types in another great division 

 (Polyzoa) could possibly be sustained. 



Fig. 233. — Tangential section of Fistulipora tri- 

 foliata, from the Middle Devonian of Gerolstein, en- 

 larged about forty times, showing the trifoliate auto- 

 pores (a) and the interstitial mesopores (7/z). (After 

 Nicholson and Foord.) 



The type-genus of the Fistuliporoids is Fistulipora itself, in which the 

 variously shaped corallum is composed of oval or cylindrical autopores, 

 which are furnished towards one side with two longitudinal folds 

 ("pseudosepta"), giving to the tubes in cross-sections a characteristic 

 bilobed or trifoliate appearance (fig. 233), and which are separated by one 

 or more rows of mesopores (fig. 234, d). The walls of the mesopores are 

 ncompletely developed, and their tabulae therefore coalesce to give rise 

 o a vesicular tissue occupying the spaces between the autopores (fig. 

 234, e). Acanthopores are occasionally developed, and in some cases 

 pseudoseptal spines have been observed. 



The species of Fistulipora are Silurian, Devonian, and Carboniferous, 

 and are m general readily recognised by the trifoliate form of the auto- 

 pores in cross-sections, the abundance of the mesopores, and the fact that 

 the tabulae of the mesopores coalesce to form a tissue of lenticular vesicles 

 occupying the spaces between the autopores, and resembling the simi- 

 larly formed vesicles which separate the autopores in Plasmopora and 

 Propora. In some forms, the two pseudoseptal folds which are so char- 

 acteristic of the genus are little developed (compare fig. 234, D, with fig. 

 233), and the trifoliate shape of the tubes is proportionately obscured. 

 The peculiar horse-shoe-shaped sinus along one side of the autopores, 

 formed by the pseudosepta, has been considered, with much probability, 

 as corresponding in the living animal with a ciliated groove (" siphono- 

 glyphe ") such as is found in the oesophagus of the Alcyonarians. Another 

 characteristic feature in many species of the genus is that the portion of 

 the wall bounding the sinus just spoken of is considerably thickened, and 



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