678 ZOOPHYTES. 



GENUS I. MOPSEA. LAMOUROUX. 



articulis cornets et calcareis alternis instructs, e internodiis cor- 

 nets ramosce ; cortice tenui. 



Isinae having the joints alternately calcareous and corneous ; ramose, 

 with corneous axils ; cortex thin. 



The Mopsese are slender fragile species, with a thin cortex. The 

 calcareous joints are long and smooth, while the corneous, which con- 

 stitute the axils of the branching zoophyte, are short. The formation 

 of the latter is connected with the periodical developement of buds 

 which occasions the branching, corneous basal secretions taking place 

 at that time. 



This genus was separated from Isis by Larnouroux; but Ehrenberg 

 first mentioned the important characteristic of the group, the fact of 

 the species branching from the corneous joints, instead of the calca- 

 reous, as in the species of Isis. 



Arrangement of the Species. 



*1. M. dichotoma. 3. M. gracilis. 



2. M. encrinula. 4. M. erythrsea. 



1. MOPSEA DICHOTOMA. (Pallas.) Lamouroux. 



M. 5" alta ; ramosa, dichotoma, ramulis 1'" crassis, articulis lapideis 

 latere compressis, aut subcylindricis ; caule 3'" crasso. 



Five inches high; ramose, dichotomous, branchlets 1 line thick; 

 calcareous joints laterally compressed or subcylindrical ; main stem 

 3 lines thick. 



Indian Ocean. 



Hippuris corattoides cornea Capensis,geni- Isis dichotoma, Schweigger's Handl).. 434. 



culis limosis, Pettiveri, Gazoph., 7, Tab. , Lamk., ii. 475, No. 3. 



3, fig. 10. Mopsca dichotoma, Lamouroux, Pol. flex., 



Isis dichotoma, Pallas, Zooph., No. 143. 467; Exp. Meth., 38. 



, Linn, ed. xii., 1287. , Dcs!ongchamp.s, Encyc., 558. 



, Esper, i. 43, tab. 5; the calcareous , Ehrenberg, G. Ixxviii., sp. 1. 



joints are about half an inch long. 



