440 Deep-sea Trawling off the S.W. Coast of Ireland : 



Echinus microstoma, Wyv. Tiioms. 

 (PI. XIX. fig. 1.) 



There is certainly among these Echini a species distinct 

 from E. acutiis or E. esculentus ; it has a bri^^iit red test and 

 that test is depressed and thin. It is a little doubtful how 

 much stress should be laid on colour and particularly red 

 colour in Echinoderms ; depressed tests may certainly be seen 

 in specimens of species which are not always characterized by 

 their possession; but the thinness of these tests is quite well 

 marked. The specific name calls attention to the characters of 

 the mouth ; but smalluess and largeness are relative terms, and 

 I give, therefore, some measurements which Wy ville Thomson 

 omitted to add to his description. I have also thought it 

 necessary to refigure the species, for the representations offered 

 by Thomson are by no means good, and the differences between 

 E. microstoma, and E. elegans are hardly at all indicated, A 

 reference to figs. 8 and 9, pi. Ixviii. of Thomson's memoir 

 and to fig. 3, PI. XIX. of the present paper will show the 

 difference in the form of the C-shaped spicules of these two 

 species. 



Echinus esculentus J L. 



Two specimens, one from 50-66 fath., the other from 110 

 fath. 



Both examples are somewhat compressed instead of being 

 globose, and tend towards the '' marked variety with a tall, 

 narrow test" spoken of by Sir Wyville Thomson {t. c. 

 p. 744). The lowest recorded depth for this species that I 

 can find is 80 fath. ; Prof. Agassiz gives no specific informa- 

 tion on this point in his ' Challenger ' Report. 



* As no measurements have yet been given of this species, I give the 

 absolute values ; the percentage values, which are much more valuable 

 for the purposes of comparison, are added in brackets. There is no better 

 method for showing the range of variation. For the purposes of comparison 

 I give the following percentage measurements of a rather young E. 

 acutus, the diameter of w^hich is 51 millim. :— height 58-8, mouth 35-3, 

 anus 18. 



