Character and Distribution of thc genus Perigonimus, 485 



The case is the more interesting in this connection in that it 

 resembles veiy closely in its medusoid persons those oi Perigoiiimus', 

 and as Fewkes has indicated, if only tlie medusa stage had to be 

 considered, its aftinities with the Tubularians would certaiiily be very 

 close. In the original description of P. Jonesii the possibilities of a 

 parasitic character were intimated, though no evidence was directly 

 perceived which would establish such a relationship. The close com- 

 mensal relations of Hydractitiia^ Poclocorijne and other related forms 

 are very well know. I have often verified the observations of Miss 

 Martha Bunting in her recent paper upou this point '. That a similar 

 form of commensalism exists between P. Jonesii and the spider crab 

 seemsquite probable, but of its exact nature Icannot speak with certainty. 



Distribution. It is not yet time to propose an exhaustive 

 account of either the geographical, or bathymetrical ränge of the 

 genus, since we know too little of the hydroid fauna of the globe 

 to afford sufficient basis for even a tentative discussion of the laws 

 of its distribution. A record of the facts known is however always 

 in Order; and through such a process we may hope to contribute to 

 the general sum of knowledge, which in its aggregation may at some 

 time justify the larger undertaking. Indeed it may be said that in 

 a general way this is exactly the method by which most of our 

 knowledge of such laws have been worked out and verified. The 

 following summary of facts in reference to the special group under 

 consideration will not therefore be without value. 



The following notes on its distribution will afford a summary 

 of our present knowledge on the subject: 



In a paper entitled »Ergänzungen zu Heller's Zoophyten etc. 

 des Adriatischen Meeres 2« F. W. Pieper reports one species, P. repens, 

 as found on Shells at Pirano, Lesina, Rovigno, and Lissa. 



J. Petersen, in a report of the scientific work of the gun-boat 

 »Hauchs «3 withiu the waters of the Danish seas duriug the years 

 1883 — 86, records the following species: — P. repens^ Kattegat, etc., 

 from depths of 5 — 26 fathoms, and reports it as found also in Scot- 

 land, England, and the Adriatic sea. P. vestitus (?), Oresund (Helle- 

 bäck), also in Scotland. P. serpens (?), Hellebäck, also England. 

 P. muliicornis^ Kattegat. 



1 Journ. Morph. Boston Vol. 9 1894 pag. 203 seq. 



2 Z. Anzeiger 7. Jahrg. 1884 pag. 148. 



3 Det videnskabelige Udbytte af Kanonbaaden Hauchs Togter etc. 1893 

 pag. 377. 



