1876.]: On the Structure of the Sty last eridce. 93 



II. PreKminary Note on tlie Structure of the Stylasteridae,, a 

 group of Stony Corals whiclij like the Milleporidse^ are Hy- 

 droids^ and not Anthozoans.''^ By H. N. Moseley^ Naturalist 

 onboard H. M.S. ^ Challenger.^ Communicated by Professor 

 Wyville Thomson, F.R.S.,, Director of the Civilian Scientific 

 Staff. Heceived May 5, 1876. 



On 14th February, 1876, in lat. 37° 17' S., long. 53° 52' W., off the 

 mouth of the Eio de la Plata, the trawl brought up from 600 fathoms a 

 number of specimens of corals of the family StylasteridaB (G-ray *). The 

 specimens included six genera of the family and seven species. They 

 were all in most excellent preservation, notwithsbanding the fact that 

 they had been slowly raised from 600 fathoms, and all had their genera- 

 tive organs in fuU development. An opportunity which had long been 

 desired was thus afforded for making a detailed examination of the struc- 

 ture of the soft parts of this family, which, in the structure of its coralla, 

 shows so many points of variance from that of Zoantharian coralla. From 

 observations made on a species of Stylaster obtained from 500 fathoms 

 off the Meangis Islands, and on a Cryjjtohelia, a short account of which 

 is given in the Eoyal Society's ' Proceedmgs,' vol. xxiv. p. 63, I had 

 already been led to suspect that the Stylasteridae might prove to be 

 Hydroids, although I did not venture to express this opinion because the 

 evidence was then insufficient. The examination of the series of forms 

 obtained off the Eio de la Plata at once showed that the Stylasteridae are 

 true Hydroids. 



Unfortunately the trawl came up rather late in the day, and hence a 

 very short period of daylight was available for the examination of the 

 animals in the fresh condition ; but it sufficed for the sketching of the male 

 gonophores of a new genus of Stylasteridte (Polypora), with the stages 

 of development of the spermatozoa, and of the female gonophores of 

 Cryjjtohelia. 



Portions of the corals were preserved by means of chromic acid, osmic 

 acid, absolute alcohol, and glyceriue ; and they were subsequently 

 examined in the usual manner by means of sections. In cutting the 

 sections, a new method, described by Mihakowics, 'Arch, fiir mikro- 

 skopische Anatomie,' ii. Bd. 3 Hft. p. 386, was adopted, and found to 

 yield most astonishingly successful results. The method seems to supply a 

 w^ant long felt of a means of cutting fine sections of structures the parts 

 of which are very loosely held together, and where it is desirable to main- 

 tain the exact relations in position of parts which in the sections often 

 become entirely disconnected from one another. Mihakowics used his 

 method for sections of vertebrate embryos ; it is certainly the best pos- 

 sible method for the investigation of decalcified tissues, such as those of 

 Corals or Echinoderms. A strong jelly, composed of equal parts of gly- 

 cerine and gelatine, is used as an imbedding substance : it permeates 

 * Ann. and Mag, Nat. Hist. rol. xix. (1847)= 



