On the Development of the Pycnogons. 193 



The writer has already published his observations on the 

 development of Phoxichilidium coccineum* It may not, how- 

 ever, be altogether supererogatory to briefly reproduce some 

 of the circumstances attending the singular metamorphoses of 

 this animal, as it is principally the object of the present paper 

 to present a resum.e of the state of our knowledge respecting 

 the development of these animals. 



This species is common on our rocks at extreme low 

 water, and is doubtless familiar to most persons conversant 

 with our littoral fauna. During the winter and early spring- 

 months the females are found with large oviferous masses 

 attached to their false feet, which in course of time produce 

 curiously formed larvae (see Fig. 4). They are of a rounded 

 form, and possess two pairs of legs, a pair of foot-jaws, and 

 a rostrum ; they retain this form for a few days, and are 

 usually attached to the oviferous mass by four long filaments, 

 which -proceed from, the tips of the legs. The connection does 

 not, however, last long, for the little beings soon enter upon . 

 a free and independent existence, during which they must 

 moult, for on again meeting with them, they present a very 

 different aspect. Now comes the singular portion of their life 

 history, which to understand requires us to be somewhat 

 acquainted with a totally different animal. 



During the spring and early summer months the rocks 

 begin to furnish their annual growth of Algae and Zoophytes. 

 Conspicuous amongst the latter, oh the Durham coast, is a 

 very elegant little Hydroid Zoophyte, Goripie eximia, which, 

 for the information of those not conversant with this order of 

 animals, may be described as a tiny shrub of a horny nature, 

 bearing club-shaped polypes at the termination of each branch. 

 These polypes are produced by the gradual accumulation and 

 growth of the fleshy and chitinous substances of the polypary. 

 At first a mere short rounded stem, the terminal part being 

 less dense than the stem, an accumulation of organized 

 material takes place, which in due course developes into a 

 polype. Whilst examining some stems of this Zoophyte I 

 noticed that there were a number of sacs attached to the stems, 

 which, although a part of the polypary, were nevertheless 

 different to any growth or part of the animal. On being 

 opened, these sacs were each found to contain a curious little 

 animal of a bright red colour. The subject was followed up, 

 and it was shortly afterwards proved that the animal in 

 question was a stage in the development of Phoxichilidium 

 coccineum, in advance of the larval forms observed imme- 

 diately after escaping from the egg. Other stages were found 

 (still within the Coryne), showing further advancement, until 

 * Annals and Magazine of Natural History. January, 1862. 



