148 CATALOGUE OF THE ECHINODERMATA OF 



sometimes brought in by the fishing boats, probably from the 

 neighbourhood of the Dogger Bank. It is our largest species, 

 and one that cannot well be mistaken in its mature state ; but 

 in its young stage it presents a totally different aspect. Several 

 small Holothurians were taken in 1864 which we considered 

 were P. squamatus of Von Diiben and Koren : a few years 

 before this the late Mr. Alder obtained a similar form at Cul- 

 lercoats, which he at the time referred to the same species. 

 Recently Mr. Norman, in his " Last Report on Dredging among 

 the Shetland Isles," at page 316 writes: — "The young of 

 this species (Psolus phantapus) has been mistaken by British 

 naturalists for P. squamatus of Scandinavian authors, a spe- 

 cies which, though several times recorded, has not yet been 

 found in the British seas." This remark led me to doubt whe- 

 ther we were justified in referring our species, as recorded in 

 the dredging report for 1864, to P. squamatus. Further com- 

 munication with Mr. Norman rendered it desirable to investigate 

 the matter very carefully, for although the spicules from a mature 

 P. phantapus differed very materially from those found in our 

 little forms, Mr. Norman was of opinion that if individuals pre- 

 senting intermediate stages of growth were examined, a con- 

 necting link would be established. Through the kindness of 

 our Newcastle Museum authorities I have been enabled to exa- 

 mine several young P. phantapus from Shetland,* younger than 

 my undoubted P. phantapus, and older than the doubtful forms. 

 Externally these animals differ in a marked degree from the Holy 

 Island specimens : the spicules, as pointed out by Mr. Norman, 

 agree in their general characters and mode of growth, therefore 

 in recording the occurrence of P. squamatus an error was com- 

 mitted, as it was only the young of P. phantapus. Nothing 

 could be more dissimilar than the young and mature of this 

 animal externally, and in the spicules from the foot the differ- 

 ence is most conspicuous. A reference to the figures in plate 



* I would here record my obligations to the Rev. A. Bethune for his kindness in translat- 

 ing me Von Diiben and Koren' s descriptions of P. phantapus and P. squamatus. His trans- 

 lation was most valuable, in enabling me to realise the respective features of the species, 

 as described by these writers, who are undoubtedly authorities on the Echinodermata. 



