HOLOTHURIOIDEA 361 



3. Mid -ventral ambulacrum with a double series of well -developed 

 tube -feet ...... Patmychia Theel 



Mid -ventral ambulacrum with numerous very small retractile 

 papilla), wliich cover the whole ventral surface 



Lcetmophasma Ludw. 



1. Lsetmogone Theel. 

 (Syn. Cry odor a Theel.) 



Mouth anterior, sub ventral ; tentacles 15, non-retractile. 

 Ventro-lateral ambulacra with a single row of large tube-feet, 

 mid- ventral ambulacrum naked. Dorsal ambulacra each with a 

 single row of very elongate, flexible, non-retractile papillae. The 

 skin contains numerous wheels and, besides, simple rods or 

 cruciform bodies. 



One species, L. violacea Theel, is known from the British seas ; 

 another species, L. Wyville-Tliomsoni Theel, has been found in the 

 Bay of Biscay, off the Azores and Canaries, in depths of 650- 

 1615 m. (" Caudan ", " Princesse Alice ", " Michael Sars "), and 

 may thus be expected to occur also in the British seas ; it is 

 further knowTi from the Antarctic and the Indo-Pacific, and 

 therefore has a cosmopolitan distribution. Bathymetrical dis- 

 tribution ca. 630-3300 m. 



Key to the species of Lcetmogone known from or likely 

 to occur in the British seas. 

 Dorsal papillae usually more numerous than lateral tube -feet ; 

 thorny cruciform calcareous bodies in the skin 



1. L. violacea Theel 



Dorsal papillae less numerous than lateral tube -feet ; no thorny 



cruciform bodies in the skin . . L. Wyville-Thomsoni Theel 



1. Lcetmogone violacea Thee>\. (Fig. 213.) 



(Syn. Lcetmogone spongiosa Theel ; L. Jourdainii Petit ; 

 L. Brogniarti Perrier.) 



Lateral tube-feet large, 11-15 (16) in number ; dorsal papillas 

 slender, usually more numerous than the lateral tube-feet, ca. 

 15-25. A short genital process in the dorsal mid-line, a little 

 behind the tentacles. Four sorts of calcareous deposits in the 

 skin (Fig. 214) : wheels, simple spicules and thorny cruciform 

 bodies. The wheels are of two sorts, larger, 0- 12-0-24 mm. in 

 diameter (the largest samples in the dorsal papilla?), and smaller, 

 005-01 mm. in diameter ; the smaller wheels usually have more 

 spokes than the larger ones. The cruciform bodies are found only 



