6 PORIFERA. II. 



mentions small isocheles occurring together with large auisocheles, he says: and therefore the inequi- 

 anchorate may possibly begin its development in this form (i. e. as isochela), and he continues, how- 

 ever it does not occur in the ovular embryo of Esflcria, while the inequianchorate do. Ridley and 

 Dendv, in Challeug. Monaxonida, follow Carter completely, though they have followed the develop- 

 ment of anisochelse in E. mammiformis. They still regard the small chelae as developmental forms of 

 the large ones in the same spouge, either the question is of isochelse or anisochelse; in several places 

 however, they say possibly young forms . Levi us en, in his paper from 1893, gives an exhaustive 

 description of the growth of the chelse. In the introduction to part I of the present work I expressed 

 the opinion that in this second part I should be able to corroborate his examinations with regard to 

 a great number of forms, and this is also the case. In the descriptions of the separate species this 

 fact will be more particularly mentioned. Here, as in the other spicules, the growth takes place 

 exclusively by apposition, either simple apposition, or after fixed lines, and the younger forms must 

 always be inscribable in the older ones. The chelae and ancora: therefore begin as axes of the full, 

 or about the full length; in the chela; the beginning is a straight or curved staff with shorter or 

 longer axial bendings in either end, and tooth and alse arise gradually and grow to their full size. In 

 the ancorae the growth takes place in a similar way, but their teeth, as before mentioned, are perhaps 

 not axial bendings, but arise in another way. Vosmaer and Pekelharing, in their paper from 

 1898 quoted several times in the preceding, treat and figure the development of the anisochela in 

 M. syrinx, but their discussion contains nothing new. When they conclude, on account of their having 

 found chelse that were a little contort, we have therefore the right to say that chelae not only can 

 be derived from spicula which have the shape of C, but indeed from spicula known as sigmata , this 

 conclusion is unwarranted; developmental forms of the chelse are in no instance sigmata, and may 

 always easilv be distinguished from these; the fact that chelse may be contort, a feature that is much 

 more frequent and mav take place to a much higher degree than seems to be known by the authors, 

 proves nothing at all. 



Developmental forms of the chelse have not rarely been misinterpreted. I shall here state the 

 cases I have found. Carter (Ann. Mag. Nat. Hist. 5, IX, PI. XI, fig. 17 d and h) calls these two figures 

 with a querv bihamates ; they are developmental forms of an anisochela. He calls (ibid. 5, XV. 

 PI. IV) fig. 3 d bihamate-like spicule ; it is the developmental form of an arcuate chela. Fristedt (Kgl. 

 Sv. Vet. Akad. Handl. 21, no. 6, Tab. Ill) calls fig. 3 h spiculum c-curvato-obtusum , but regards it with 

 a query as an undeveloped chela; it is an undeveloped arcuate chela. La nib e (Trans, of the Roy. Soc. 

 of Canada, XI, sect. IV, PI. II) calls fig. 4 c a sigma; it is a developmental stage of a palmate anisochela. 



Levin sen, in his paper from 1893 several times quoted above, after having established the 

 fundamental difference between chelse and ancorse, and rendered an account of the fact that they are 

 never found together, expresses the opinion that this fact must involve the alteration in the system 

 that species with chelse and species with ancorse cannot be kept in one genus. I can fully agree with 

 this view, and therefore in the present work I have separated the species according to it. In this 



