It is probable that the occasional phenomenal swarms of _Doliolum_ which have been met with in summer in the North Atlantic are a result of the curious life-history which, under favourable circumstances, allows of a small number of oozooids producing from minute buds an enormous number of phorozooids and gonozooids. As the result of the careful quantitative work of the German "Plankton" expedition, Borgert thinks that the temperature of the water has more to do with both the horizontal and the {100}vertical distribution of these Thaliacea in the sea than any other factor. OTHER GENERA.—_Anchinia_, of which only one species is known, _A. rubra_, Vogt, from the Mediterranean, has the sexual forms permanently attached to portions of the dorsal outgrowth from the body of the unknown oozooid ("nurse"). The stolon is probably much longer than in _Doliolum_, and curves round so as to reach and lie along the dorsal outgrowth, upon which it places the buds. The body of the adult is elongated dorso-ventrally. The test is well developed and contains branched cells. The musculature is not so well developed as in _Doliolum_. There are two circular bands at the anterior end, two at the posterior, and two muscles on the middle of the body, which unite to form the characteristic S-shaped lateral bands. The stigmata are confined to the obliquely-placed posterior end of the branchial sac. The alimentary canal forms a U-shaped curve. The reproductive organs are placed on the right side of the body. The life-history is still imperfectly known. As in the case of _Doliolum_ the sexual generation is polymorphic, and has three forms, two of which remain in a rudimentary condition so far as the reproductive organs are concerned. They are known as the first and second sterile forms, or "trophozooids." In _Anchinia_, however, the three forms do not occur, so far as we know, together at the same time on the one outgrowth, but are produced successively, or in different regions, the reproductive forms of the sexual generation being independent of the "foster-forms."[106] The third genus, _Dolchinia_, contains also only a single species, _D. mirabilis_, found by Korotneff[107] in the Gulf of Naples. It must have three different forms in its life-history—oozooid, phorozooid, and gonozooid, but the first of these is still unknown. On what must be body processes detached from the oozooid are found phorozooids somewhat like those of _Doliolum_, bearing sexual forms attached to ventral stalks. _Dolchinia_ is intermediate on the whole between _Anchinia_, the most simple member of the family, and _Doliolum_ the most complex; and may eventually come to be united with the latter genus. {101}SUB-ORDER 2. HEMIMYARIA.