452 SUMMARY OF CURRENT RESEARCHES RELATING TO 



objects that touch it. In addition to their offensive functions, the 

 spines are also of importance as sensory organs. 



In conclusion, the authors have a few remarks on the anatomy of 

 this Echinothurid ; they draw attention to the five pairs of well- 

 developed longitudinal muscles which serve to depress the test ; these 

 are inserted by pairs into the auricles ; morphologically, they are _ of 

 importance as bearing on the comparison of the Echinothurids with 

 Holothurians. 



A small fish, whose ground colour is that of A. urens, and a small 

 macrurous Decapod of similar colour, live commensally with the 

 urchin ; on Diadema setosum there is a closely allied fish ; both, when 

 frightened, hide among the spines, as if fully conscious that they 

 would be there quite safe. 



New Organs of the EcMnida.* — Dr. 0. Hamann, under the 

 title of globiferi, describes some organs in SjphserecUnus granulans, 

 which have an extraordinary resemblance to one form of pedicellaria, 

 as described by Mr. W. Percy Sladen, in the same Echinid ; no 

 reference to the earlier writer is, however, made by Dr. Hamann, 

 who describes the bodies as glandular organs which emit a secretion 

 through apertures ; he is reminded by them of the mucigenous cells 

 of Vertebrates. 



Transversely striated Muscles in Echinida.t — Dr. O. Hamann, 

 who has vainly sought for transversely striated muscles in Holo- 

 thurians and Asterids, has now detected them in the pedicellarias of 

 Echinids. The fibrils if examined in the living state distinctly show 

 the transverse striation; the individual fibrils when, as they may 

 easily be, separated from one another, are seen to have attached 

 externally a large elongated oval nucleus. 



Coelenterata. 



Cyclic Development of Siphonophora.l — Prof. C. Chun continues 

 his researches on Siphonophora, especially on Monophyidse, supporting 

 and extending what he has previously maintained in regard to the 

 cyclic development of the latter. 



I. The cyclic development of Monophyidse. — All the Monophyidaa, 

 viz. Muggisea KocMi, Monophyes irregularis, and Monopliyes gracilis, 

 are independent species, whose primary swimming-bells are thrown 

 off, and replaced by final heteromorphous bells, of which only one is 

 present Prof. Chun maintains, against Claus, that Muggisea is a 

 Monophyid and not a Diphyid. The primary bells may be regarded 

 either as " nurses " from which the stem and the reserve bell are 

 budded off, or as larval forms, according as most importance is attached 

 to the preponderant development of a distinct bell of considerable 

 size, or to the analogy with the alternation of heteromorphous 

 protective organs and tentacles in other Siphonophora. 



* Add. and Mag. Nat. Hist , xvii. (1886) pp. 386-7. 

 t Tom. cit., p. 338, from SB. Jenaisch. GeselL, 188G. 

 i Sli. K. PrcjUBS. Ak;id. Wiss., 1885, pp. 511-2'J (1 pi.). 



