904 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(stichopod) or scattered over the surface of the body (sporadipod) ; 

 some of the stichopod forms are armed with a rich supply of cal- 

 careous plates in their integument, and these are distinguished from 

 the unarmed forms. Having thus arranged the genera in three 

 groups, he takes as his second point of distinction the character of 

 the tentacles ; of which there may be ten radial and subequal, or ten 

 radial, of which one pair is smaller than the other four ; or more 

 than five pairs. A phylogenetic table is given showing the affinities 

 of the genera in relation to these co-ordinates. 



Cuvierian Organs of the Cotton -Spinner.* — Prof. F. Jeffrey 

 Bell gives a technical account of this almost unknown British Holo- 

 thurian, which is of interest as being the only true — that is aspido- 

 chirotous (or with shield-shaped tentacles) — member of the class 

 which is known to occur in the British seas.j The organ of most 

 importance is that which produces the sticky secretion from which 

 these animals have obtained their name, and which makes them objects 

 of much dread to the Cornish fishermen. The producing or Cuvierian 

 organs are described as forming a solid mass which occupies a 

 large portion of the body-cavity, and which is made up of a number 

 of separate tubes ; a small coiled portion was found lying in the 

 cloaca as if ready for ejection. A small piece of a tube measuring 

 only 2' 5 mm. was found, even after twenty years' immersion in 

 spirit, to be capable of extension to twelve times its own length ; 

 while, when treated with water, the attenuated thread swells up to 

 seven times its own breadth. " We can thus understand that an animal 

 at whom these threads are thrown should, as it attempts to escajpe, 

 lengthen the threads which, at the same time, coming into contact 

 with the water, would be swollen out transversely as they were ex- 

 tended longitudinally." Prof. Bell thinks that the observations 

 confirm the view of Semper as to the protective or offensive character 

 of these organs, which by Jiiger and most later anatomists have been 

 thought to be renal in function. 



In a subsequent note | Prof. Bell states that six threads, any 

 one of which was only barely visible, were capable of supporting a 

 weight of nearly a thousand grains ; and § quotes a letter from a 

 correspondent to say that the black Holothurians near Porto Fino 

 emit a tangled mass of white threads so sticky and in such quantity, 

 that it was difficult to free the hands from them. 



Porifera. 



Vosmaer's Sponges — The sixth part of this work II (pp. 145-76 

 with plates XV .-XVIII.) has been published. The skeletal system 

 is here entered upon, and, after an account of various systems of 



* Proc. Zool. Soc. Lond., 1884, pp. 372-6. 



t H. intestinalis of Norway has been found in the Minch. 



X Nature, xxs. (1884) pp. 146-7. 



§ Op. cit., p. 194. 



il See this Journal, ante, p. 897. 



