MB. P. H. CABPENTEE ON THE GETSTUS ACTINOMETBA. 441 



the mouth is subcentral. All these, as for example the British 

 Antedon rosacea, have the five centripetal ambulacra characteristic 

 .of Alecto ; but there are many species of Alecto, as for example G. 

 (Alecto) multiradiata, in which the five primary ambulacra converge 

 to an excentric or even marginal peristomial area, the mouth being 

 nowhere near the centre of the disk. Such forms as these clearly 

 have no place in the genus Antedon, while they are excluded from 

 Actinometra, as defined by Miiller, although agreeing with it in the 

 excentric position of the mouth. In many Comatuloe also, the mouth 

 is excentric, and six, eight, or even ten groove-trunks reach the 

 peristom ; these, again, have no place either in Antedon, Alecto, or 

 Actinometra (as defined by Miiller). 



After a careful examination of a large number of Gomatulce, 

 including the valuable collection in the Paris Museum, and 

 also a number of new species brought by Professor Semper 

 from the Philippine Islands, the author has been led to the con- 

 clusion that Miiller's mode of classification of the Comatulce is 

 purely artificial, and leads to the separation of individuals which 

 really belong to one and the same species : on the other hand, the 

 position of the mouth, either subcentral or excentric, alfords a very 

 natural means of classification, being readily visible externally, 

 and being also accompanied by important difierences in the ana- 

 tomy and relative positions of the internal organs. 



The author has examined eleven specimens of Gomatula poly- 

 morpha, in all of which the mouth is excentric, and the composi- 

 tion of their skeleton and other parts so similar that they evi- 

 dently belong to one species. One of them, however, would have 

 been referred to Alecto by Miiller, having five primary groove- 

 trunks, and another, with only four, to Actinometra ; but there is 

 no place in his system for the remainder, which have six, seven, 

 or eight groove-trunks reaching the excentric peristom. Miiller 

 himself aiFords us similar examples of the artificial nature of his 

 classification; for in one place he describes a specimen as Actino- 

 metra, while a little further on he classes it as Alecto, on account 

 of the similarities it presents to A. multiradiata in the characters 

 of the skeleton. 



Again, Miiller, who examined the Paris collection of Gomatulce, 

 does not describe the C. trichoptera which he found there, either 

 as Alecto or as Actinometra, the reason probably being that there 

 are only four primary groove-trunks in one of the two specimens, 



LINN. JOUBN. — ZOOLOGY, VOL. XIII. 37 



