ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 485 



The development of the tetraspores and spermatia is described. The 

 carpogonial branch arises as a lateral outgrowth of a large subcortical 

 cell. A mature carpogonial branch consists of six or seven cells and a 

 trichogyne. The basal cell sometimes divides to form a lateral cell. 

 Each carpogonial branch which has been fertilized produces two or three 

 sporogenous filaments, all of which arise from one cell. It is thought 

 that the nuclei in these filaments are descended from the fusion nucleus 

 in the carpogonium. The sporogenous filaments grow out towards the 

 auxiliary cell branches. The auxiliary cell branches in origin, distribu- 

 tion, structure, and mode of development are very similar to the 

 carpogonial branches. Only about one auxiliary cell-branch is initiated 

 to every seven carpogonial branches. The time of initiation of the 

 former is a little later than that of the latter. The mature auxiliary 

 cell-branch consists of four to seven cells. The second or third cell of 

 the branch is the auxiliary cell. The original nucleus in the auxiliary 

 cell takes no part in the formation of the carpospores. The nuclei in 

 the carpospores are descended from the nucleus which enters the 

 auxiliary cell from the sporogenous filament. In the development of the 

 carpospores and cystocarps three or four gonimoblast filaments arise from 

 the auxiliary cell. Every cell of these filaments forms a spore. There 

 are about twenty carpospores in each cystocarp. Mature carpospores are 

 usually uninucleate, well filled with a cytoplasm, and contain chromato- 

 phores, which are similar to those of the vegetative cells. In the resting 

 nucleus of Dumontia all the chromatin is in the nucleolus. The 

 nucleolus often contains a vacuole. The chromatin in preparation for 

 mitosis passes out of the nucleolus, and in the form of small granules 

 l)ecomes distributed along the linin net. The net disappears and the 

 granules become massed together to form larger units, chromosomes. 

 The number of chromosomes was not definitely determined, but was, 

 apparently about seven. No spireme or spindle was seen. After division, 

 the chromatin is again found massed in the nucleolus. 



Calcareous Alg-se from Malta.* — C. Samsonoff-Aruffo describes 

 certain calcareous alg^ collected from the Upper Coralline Limestone in 

 Malta. The first of these, LitJiopkyllimi Destefanii, a new species, is 

 described in detail. The tballus forms numerous thin laminre, which 

 are superposed and united by small bands of cemented sand. The 

 hypothallus and perithallus are clearly to be distinguished, and show the 

 characters of Lithophyllum. The thallus is sterile. It is most closely 

 allied to L. lichenoides and L. Fosliei. Another species was collected in 

 the Lower Coralline Limestone It forms part of a mixture of incrusta- 

 tions and of very short swollen branches closely united by a basal 

 calcareous mass. When separated out, the alga shows a hypothallus 

 which is but slightly developed, though always present, and of the type 

 of Lithothamnium. The perithallus is more developed, very compact 

 and regular, composed of vertical cellular columns of very small cells. 

 The structure is described in detail. The alga, which is most closely 

 allied to L. compactum, is called by the author, L. miocenum, a new 



* Atti (Rend.) R. Accad. Lincei Roma, xxvi. (1917) pp. 610-6. 



