388 Mificell anemia . 



either intended to siiljstitnte it for the other, or that he had been 

 balancing between the two and had unfortunately chosen to adopt 

 the bad one. 



Dr. Stokes now writes to say that the name Diplomastax (which 

 wois no doubt at first adopted by him for his genus) is preoccupied 

 among the Flagellate Infusoria, and to request that his name 

 Dlplomestoma may be substituted for it as that of the genus in 

 question. 



Striated 3Iiiscles in Echinidn. By Dr. Otto Hamann. 



While transversely striated muscles are known in many groups of 

 the lower animals, hitherto only smooth muscular fibrillte have been 

 known in the Eehinodermata. In Holothurite and Asterida I have 

 sought in vain for transversely striated fibres *, but I have now 

 succeeded in finding them in the Echinida. They occur, however, 

 only in a feAV places, and, indeed, in places where a sudden, rapid, 

 and energetic contraction has to take place. The largest forms of 

 pediceUarife, the pedicell. tridentes s. iridaciyles, are best fitted for 

 examination. 



The musculature which moves the three arms consists of parallel 

 fibrillje, which, if examined in the living state, distinctly show the 

 transverse striation. The individual fibrillte may be easily sepa- 

 rated from each other, and then it appears that each fibril has 

 attached to it externally a large, elongate oval nucleus, which is 

 situated about in the middle of the fibril. It is but rarely that any 

 plasma is still demonstrable around this. If it be pulled to pieces in 

 picro-carmine and afterwards examined in glycerine, the lighter and 

 darker transverse striae, and, in the former, Krause's transverse 

 disks, make their appearance distinctly, as also the thin sarcolemma. 

 The diameter of the nearly cylindrical fibrillte is about 0"0028 millim. ; 

 their length in the pedicellariae of CentrostepTianus longispinus, 

 Peters, is between 0*5 and 0*6 millim. 



Now and then we maj' detect a longitudinal striation in the 

 fibrillse ; and when treated with various liquids, each fibril breaks up 

 into a number of exceedingly fine parallel elements (I cou)ited4-6) 

 which still show the transverse striation distinctly. 



The species which I have been able to examine, in which trans- 

 versely striated musculature exists, are as follows : — Centrostephanxs 

 longispinus, Peters; DorocidarispapiUata, A. Agass. ; Arhacia piis- 

 tulosa, Graj' ; Strongylocentrotus lividtis, Brandt ; tSphcer echinus 

 granularis, A. Agass. ; Echinus ncutus, Lam. ; Echinus melo, Lam. ; 

 and Echinus microtuberculafiis, Blainv. — Sitzungsberichte der Jena- 

 ischen Gesellschaft ficr Medicin und Naturwissenschaft, 1886. 



* Hamann, ' Beitrage zur Ilistologie der Echinodermen : Heft 1. Die 

 Holothurien ; Heft 2. Die Asterideu anatomisch und histologisch unter- 

 Bucht' (Jena, 1884-85). 



