164 



HYDROIDA II 



600 m. 



. _ to 00 m. 



Fig. LXXXIV. The occurrence of Camj>anularia Johnstoni in the northern Atlantic. 

 In the hatched region a common occurrence is stated. 



Gen. Laomedea Lamouroux. 



Upright, sympodial colonies only occasionally exhibiting creeping parts with nnbranched polyp 

 stalks. The hydrotheeee have a typical broad diaphragm which forms the boundary between the main 

 cavity and the basal chamber. The polyps can be withdrawn entirely into the radially symmetrical 

 hydrothecre. The hydranth has a clnb-shaped proboscis, and homogeneous gastral endoderm. 



Lamouroux (1812) gave the following diagnosis of the genus: "Polypier phytoide, rameux; 

 cellules stipitees ou substipitees, eparses sur les tiges et les rameaux". This thus embraces the up- 

 right colonies of Camfianulariidce, but Lamouroux has nevertheless placed Campanularia verticillata 

 in his genus Clytia. There is thus no reason to suppress the name Laomedea for later and more 

 narrowly restricted genera, and we cannot, on phylogenetic grounds, break up the genus as here defined 

 on account of the biological peculiarities apparent in the gonophores. Nor is a better survey obtained 

 by dividing the genus according to the nature of the gonangia, which it is in most cases impossible 

 to determine with certainty from the colonies obtained. And that characters should be easier to handle 

 when raised to generic rank than when applied to species it is not easy to understand. 



In this genus, we find quite exceptionally that certain species, such as Laomedea dichotoma 

 (Linne) may occur with creeping growth modification (cf. Broch 1913 p. 55); in such case, however, 

 the diaphragm distinctly shows to what genus the species must belong. These creeping parts are 



