M. F. Muller on th& Systematic Position Of the Charybdeidee. 1 L 



of Cunina, with its simple proteiform mouth, closely repeated in 

 jEgineta, Polyxeniu, and JEginopsis bitentaculata, the four arms 

 on the mouth of ^Eginopsis Laurentii, Brdt., lead to the struc- 

 ture of the stomach in Charybdea and Tamoya. In the same 

 way the form of the sexual organs of Tamoya may be deduced 

 without constraint from those of Cunina ; but neither the one 

 nor the other can be referred .to the fundamental form deve^ 

 loped in Hydroida and Acalephse. If Tamoya quadrumana has 

 an entire series of perfectly new parts not even indicated in Cu- 

 nina, such as a well -developed nervous system, there is nothing 

 remarkable in this ; some of them, such as the eight finger-like 

 processes in the base of the bell and the dendritic glands, are 

 totally wanting even in T. haplonema. 



The formation of the marginal corpuscles is certainly essen- 

 tially different ; but we still know nothing about their develop- 

 ment in Charybdea and Tamoya, or of their structure in the 

 intermediate forms JEgina citrea and JEginopsis Laurentii; and, 

 again, their difference is not more considerable than between 

 the eye-spots and marginal vesicles of the Hydroida. 



The formation of the tentacles also is perfectly anomalous, 

 but nevertheless by their dorsal origin they contrast equally with 

 the marginal filaments of the Hydroida and Acalephae. The 

 tentacles of Cunina are rigid, those of Tamoya contractile ; but 

 those of the young brood of Cunina are also contractile. The 

 tentacles of Cunina are solid, those of Tamoya hollow ; but hol- 

 low and solid tentacles are exhibited by otherwise very nearly 

 allied genera, such as the various Campanularia-buds* ; nay, both 

 forms occur simultaneously or successively in the same animal 

 {Liriope). In this, therefore, no ground for the union of our 

 two families can be sought ; but that which especially speaks in 

 favour of it is that at present it is not possible to draw a marked 

 boundary-line between the two, and to refer the median forms 



, * For the Campanularia-hu&s with solid and but slightly moveable 

 tentacles, exactly like those of Campanularia itself, I propose to retain 

 Dalyell's name Tintinnabulum ; it appears that they are always born with 

 a greater number of tentacles. Here belongs also Eucope polystyla, Ggb. 

 What Gegenbaur describes and figures in this species as roundish inflations 

 of the annular vessel, directed into the substance of the disk, may be the 

 thickened roots of the tentacles, judging from the nearly allied Tintinna- 

 bulum resupinatum, n. sp. The Ca?nj}anularia-huds with hollow filaments 

 dilated at the base and very contractile, of which, when set free, they have 

 only four and the first traces of four more (Eucope, Ggb., excl. E. poly- 

 styla), have, in my opinion, a title to the name of Thaumantias; for it 

 appears to me scarcely doubtful that it is to these, and not to T. mediter- 

 ranea, Ggb., that the two Eschscholtzian species of Thaumantias belong ; 

 and for them, therefore, in a division of the genus, the old name should 

 be retained. 



