HOLOTHURIOIDEA 



381 



1. Mesothuria intestinalis (Ascanius). (Fig. 228, 3.) 



(Syn. Holothuria intestinalis Ascanius ; Atlantis intestinalis 

 (Asc.) Herouard.) 



Mouth subventral, anus posterior. Tentacles 20 in adult, 

 fewer in younger specimens. Tube-feet most strongly developed 

 in the ventro - lateral ambulacra, but no distinct longitudinal 

 series there of larger tube-feet ; on the dorsal side they are fewer 

 and smaller, and especially they are very scarce along the mid- 

 ventral radius, which appears almost naked. The calcareous 

 deposits (Fig. 225), which lie very closely in the skin, are tables 

 of the 4-radiate type, with a spire built of 4 rods, ending in a 

 crown of several thorns ; disk 

 often with some small holes out- 

 side the primary circle of peri- 

 pheral holes. In quite small 

 specimens the spire may be com- 

 posed of only 3 rods. Tables of 

 the tube-feet well developed, Uke 

 those of the skin. Colour in life 

 greyish-white, often with a faint 

 pink or violet tint. Often pale 

 brown in alcohol. Grows to a 

 length of ca. 30 cm. 



The species is hermaphrodite, 

 but male and female products 



are not found ripe at the same time. Eggs large and yolky ; the 

 development, therefore, probably direct, without a pelagic larval 

 stage. It lives on muddy bottom and usually covers itself with 

 shell fragments and other bottom material. It is rather difficult 

 to preserve, as it usually eviscerates itself during capture. 



In British seas this species has been found repeatedly off 

 S.W. Ireland, in ca. 340-1350 m. ; it is further recorded from 

 Kilbrennan Sound, the Clyde, and the Minch, in ca. 50-100 m. 

 depth. The species is elsewhere distributed from the Murman 

 coast to the Azores and the Mediterranean. Bathymetrical 

 distribution ca. 20-2000 m. 



Fig. 225. — Calcareous deposits 

 (tables) of Mesothuria intestinalis, 

 seen from above and in side view. 

 X 145. {From Danmark's Fauna.) 



2. Mesothuria Verrilli (Theel). 

 (Syn. Holothuria Verrilli Theel ; Atlantis intestinalis, var. 



Verrilli (Theel) Herouard ; Holothuria Roulei Koehler.) 

 Differs from the preceding species in the tube-feet being 

 smaller and very closely set in the posterior part of body, which 



