2J00L0GY AND BOTANY, MICROSCOPY, ETC. 667 



showing that they are not homologous with these structures ; (2) the 

 occurrence of synapticula whose structure is seen under the Micro- 

 scope to be discontinuous with that of the septa ; (3) the synapticula 

 in some cases showing a flat surface when the septum is broken off 

 from it ; * (4) the basal wall being formed of fused synapticula. In 

 Fungia echinata the synapticula are more slender, are vertical instead 

 of oblique, and near the circumference form series of granules instead 

 of ridges. 



In the multi-caliculated genus Herpoliiha (HerpetoUtha auctt.) the 

 faces of the septa exhibit an ornamentation consisting of ridges and 

 granules, varying in different parts, and none of the septa are per- 

 forated, as is the case in Fungia. The synapticula are either curved 

 or vertical ; towards the margin of the corallurn they may be repre- 

 sented by discontinuous knobs ; sometimes the surface which is 

 usually in contact with the septum is found free. - 



Of Halomitra, a genus which includes Podabacia and part of 

 Fungia of Milne-Edwards and Haime, H. Crustacea Kumphius was 

 examined. In the large centre calicle the septa may be either solid 

 or fenestrate ; but in the latter case the hard trabeculse are very solid 

 and well defined. The synapticula are usually vertical ; and where 

 the septa are fenestrate they are either confined to the non-fenestrate 

 part of the septum or else maintain their own continuity by winding 

 along its trabeculse. 



In the group generally the synapticula are grooved in two direc- 

 tions ; they are as stout between thin as between thick septa. The 

 hard, " fibrous " structure of the corallum is composed of elongate 

 prisms or fusiform spicules. Prof. Duncan has found soaking the 

 corals in weak carmine solution a useful plan for bringing out the 

 more minute ornamentation and sculpture of the septa. 



Porifera. 



Ovum of Marine Sponges.t — H. J. Carter has discovered the 

 presence of starch-granules in the ovum of Marine Sponges. First 

 observed in Suherites domuncula, where the yolk contains starch- 

 granules of a greyish-white colour, the observation has since been 

 extended to Isodictya simulans, Halisarca lohularis, and others, where 

 evidence was afforded as to the animal nature of the organisms " in spite 

 of the resemblance of the ova of sponges to the seed of plants, inas- 

 much as it was found that the sponge-embryo developes a root for 

 fixation only, and a superstructure for supporting organisms that take 

 in crude material for food." 



The author makes a few observations on the characters of the 

 spermatozoa of sponges, and expresses his opinion that, even with the 

 late observations of Polejaeflf on Sycandra raphanus, there is not yet 

 any character given to the spermatic cell by which it may be satis- 

 factorily recognized by the inexperienced student ; and he concludes 



* The author, however, admits that in some cases the synapticulum is a 

 septal structure. 



t Ann. and Mag. Nat. Hist., xii. (1883) pp. 30-6. 



