438 Deep-sea Trawling off the 8.W. Coast of Ireland : 



One of the most interesting discoveries of the Drs. Sarasin 

 was that of the muscles which divide the test into a series oi 

 compartments and appear to be the agents in the vermicular 

 contractions of the living test ; this again they have made one 

 of the characteristics of tlie Echinothuriidai, and here, again, 

 they have unfortunately argued from the particular to the 

 general. These " Langsmuskeln " are altogether absent from 

 Phormosoma. An interesting proof of this may be easily 

 afforded : if a Phormosoma be opened and water poured into 

 the test the whole test swells up ; if a quadrant of an Astheno- 

 soma be laid open and water poured in the whole test does not 

 swell up, and such a specimen if returned to spirit will be 

 found to float with one quadrant upwards, just as though 

 it were provided with air-tight compartments ; these, of 

 course, are the " Kiistchen" of the Sarasins. I am not, how- 

 ever, sure that, even confining ourselves to the genus Astheno- 

 soma, as at present defined, we can always speak of the 

 longitudinal muscles as being well developed ; they certainly 

 are remarkably well developed in Asthenosoma O-rubiij but 

 they are very poorly so in the smaller A. jjelliicidum. With 

 the absence of the muscle is correlated that of the Kiistchen, 

 and with that of the Kiistchen the peculiar loop of intestine 

 in each alternate compartment. I do not like to lay too much 

 stress on the apparent absence of the organs of Stewart from 

 Asthenosoma Oruhii and A. pellucidum ; delicate membranes 

 might well be injured or collapsed in specimens all of which 

 were collected before 1876 (that is, of course, during the 

 cruise of H.M.S. 'Challenger'), and I am not saying they 

 are not to be found in all species of Asthenosoma ; I have, 

 however, some doubt as to whether or no they are so large or 

 so constant as they seem to be in A. urens. 



However that may be, the condition which obtains in 

 Phormosoma shows that the large size of the organs of 

 Stewart is not a character of the Echinothuriida3. I need not 

 press this point further by urging that this single fact will 

 dispose of a good deal of the speculation whicli made Messrs. 

 Sarasin's essay more than usually interesting. 



Six specimens were dredged at 1000 fath , five of which 

 are in the possession of the British Museum ; the colour of 

 the test preserved in alcohol varies from lightish yellow to a 

 distinct purplish colour ; in all cases, unfortunately, the 

 spinulation is practically destroyed. 



