Sept. 1, 1SG9.1 



HARDWICKE'S SCIENCE-GOSSIP. 



199 



be found on the shore. The stem is slender, and 

 twisted like a corkscrew; the branches are all nearly 

 of the same length, spirally arranged upon the 

 stem, and when dry are curved like a sickle. The 



o 



3n> 



Fig. 147. Thuiaria thuia, magnified. 

 b. capsule. 



Fig. nO. Thuiaria thuia, 

 nat. size. 



Fig. 14S. Hydrallmnnniafaleata, 

 magnified, a. capsule. 



cells, or calycles, are only on one side of the 

 branches, closely crowded together (fig. 148), and 

 the capsules are abundant in the spring, pear- 

 shaped, a little ribbed longitudinally when dry, with 

 slightly contracted tubular mouth (fig. 148, a). 



In all the remaining species which are included 

 amongst Sertuiarians, the cells are projecting, 

 and in rows on opposite sides 'of the stem. All 

 the species which are now united in the genus Ser~ 

 tulariella (with one exception) are very small. The 

 cells are distinctly alternate, and usually at a greater 

 distance apart than in the other groups. The 

 mouths of the cells are always toothed, and are 

 closed by a prominent operculum. 



The first species is the " Great Tooth Coralline " 

 {Set -tulariella polyzonias), which is the commonest 

 of all, and occurs on shells, seaweeds, and other 

 zoophytes all around the coast. It is very variable 

 in size, and in the form of the calycles, sometimes 

 not more than half an inch in length, and sometimes 

 forming plant -like masses. The cells have four 

 teeth on the margin (fig. 149), and the capsules are 



ovate, and wrinkled transversely throughout then- 

 length; the mouth of the capsules is tubular, sur- 

 mounted by four teeth (fig. 149, a). The male and 

 female capsules differ considerably in size and 

 colour. 



-x. - 



Fig. 149. Sertulariella polyzonias, magnified, a. capsule. 



Another species with pinnate branches {Sertu- 

 lariella Gayi) is found on the Cornish coast, and a 

 few other localities. The cells are very similar, 

 sometimes a little wrinkled transversely in this 

 species, but the capsules are distinct, for the mouth 

 is only two-lipped, and the upper half only of the 

 capsule is transversely wrinkled. 



Mr. Alder found a third species as a parasite 

 on zoophytes, brought in by Newcastle fishing- 

 boats, but it is too rare to require further notice 

 here. 



The "Snail Trefoil Coralline" {Sertulariella 

 rugosa) is found on the " sea-mat," seaweeds, and 

 other zoophytes. It is less than an inch in height, 

 either erect or creeping. The cells are barrel- 

 shaped, and ribbed transversely (fig. 150). The 

 capsules are three or four times as large as the 

 calycles, similarly shaped and ribbed, with a four- 

 toothed orifice (fig. 150, a), one of the teeth being 

 very minute. 



Two other species are rare {S. tenella and 

 S.fusiformis), and both very small. 



The fifteen British species which are divided as 

 equally as they can be between the two genera, 

 Diphasia and Sertularia, might be classed artificially 

 two or three ways into two divisions. For instance, 

 some have the cells or calycles opposite each 

 other in parts, others have them alternate. Again, 

 although all are more or less branched, some have 

 the branches pinnate, or arranged in a feathery 

 manner, and in others the branching is forked or 

 irregular. But the division into two genera which 



