226 7hc Irish iVafuralist. December, 



character relied on is the form of the head-appendages. 

 These are described by Alder in vol. v. of Jeffreys as "short, 

 fiat, whitish tentacular processes " in .4. corrugata, as " linear 

 and cylindrical tentacles of moderate length," in^. Cocksii. 

 Minor distinctions as to colour and size are mentioned, 

 0*12 inch being given as the length of the first and 0*2 

 inch of the second species. The body of A. corrugata, 

 moreover, is said to be regularly wrinkled in a longitudinal 

 direction, while in A. Cocksii it is given as smooth. In 

 the plates, however, these wrinklings or corrugations are 

 shown as ver\^ inconspicuous and apparently no more 

 marked in one species than in the other. They occurred 

 on the lateral regions of all of the specimens of Actaeonia 

 I have examined, but in none were they a prominent feature. 

 Betv/een the 23rd January and the 17th March, 1909, 

 I collected a total of 67 living Actaeonias in pools at Bullock, 

 a little below high-water mark. While the form of the 

 head-appendages in a majority of these specimens was 

 such as to justify their reference to A. corrugata, in the 

 remainder these appendages varied so considerably as to 

 make it doubtful whether a given specimen should be 

 assigned to A. corrugata or A. Cocksii. The smaller in- 

 dividuals, referred to A. corrugata by reason of their blunt 

 and slightly prominent appendages, approached closely in 

 general aspect to Limapontia nigra, which occurs in asso- 

 ciation with Actaeonia at Bullock and elsewhere on the 

 Irish coasts ; but the marked difference in the egg-masses 

 furnished a decisive distinction. Both Limapontia and 

 Actaeonia were kept in captivity at the same time, and 

 both deposited eggs freely. Those of Limapontia were 

 small and numerous, at least 100 in each oblong cluster, 

 the yolk being clear yellow in a pellucid medium ; those of 

 Actaeonia were fully six times as large and few in number, 

 from 2 to 30 in a cluster, an average of 13 eggs being given 

 by 23 clusters laid in captivity. The yolk of the Actaeonia 

 G^g, moreover, was bright orange in a milky albumen 

 which rendered the clusters, small as they were (usually 

 2 mm. long) quite conspicuous on the green Cladophora 

 twigs to which they adhered. No lengthened attention 



