On the Structure of the StylasteridfB. 185 



the sketching of the male gonophores of a new genus of Stylasteridae 

 (Pohfpora), with the stages of developinent of the sp -rmatozoa, 

 and of the female gonophores of Cri/jtlnhi lid. 



Portions of the corals were preserved hy means of ehromic acid, 

 osmie acid, absolute alcohol, and glycerine ; and they were subse- 

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

 cutting the sections, a new method, described by Mihakowics, 

 'Arch, fiir mikroskopische Anatomic,' ii. Bd. 3 lift. p. 3^0, was 

 adopted, and found to yield most astonishmgly successful results. 

 The method seems to supply a want 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 maintain the exact relations 

 in position of parts which in the sections often become entirely 

 disconnected from one another. jMihakowics used his method for 

 sections of vertebrate embryos ; it is certainly the best possible 

 method for the investigation of decalciKed tissues, such as those of 

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

 of glycerine and gelatine, is used as an imbedding substance ; 

 it permeates the tissues, and takes the place of the hard calcareous 

 supporting structures which have been removed by the acid. The 

 sections are mounted in glycerine, and the imbedding substance, 

 which is left in situ in the sections, becomes perfectly trans- 

 parent, in fact almost invisible; in this fluid. i stain the de- 

 calcified corals w ith carmine, then soak them in glycerine, and then 

 transfer them directly to the warm lltud jelly, instead of treating 

 them lirst with absolute alcohol after staining, as does Mihakowics. 

 A teaspoon heated in hot water is a most convenient instrument 

 for transferring the small masses of tissue, with the fluid jelly, 

 to the cavities in the hardened liver used as an imbedding base. 

 I have dwelt upon this method because it seems to me likely to 

 be one which will prove of the greatest service in all kinds of 

 diflicult histological problems, such as Corti's organ, early stages of 

 embryos, retina, &c. It is quite possible by the method to obtain 

 sections of a single hydroid sporosac or planula. 



The Stylasteridai obtained oft' the Eio de la Plata comprised six 

 genera, viz. : — Stylaster ; C'r)/ptohelia ; Allu2>ora ; Errhia ; a nevs 

 genus, Pohfpora ; and a further new genus allied to Errina, 

 which I propose to term Avanthopora. There is much confu- 

 sion as to the determination of even the genera of the Stylas- 

 teridaj, and I have found it impossible to determine species in 

 the absence of specimens for comparison. The Stylaster appears 

 probably to be ;S'. eruhescens of Pourtales*. The C'ri//>tuhelia 

 is the same as that obtained all over the world by the ' Chal- 

 lenger ' in deep water, and apparently not specifically distinct 

 from C. jnulicwf. Of the Allopora I cannot determine the 



♦ Illustrated Catalogue of the MuBeum of Comparative Zoology at Harvard 

 College. No. IV. Deep-Sea Corals. By L. F. de Pourtales. Cambridge, Mbm. 

 1871. p. 34. 



+ Hist. Nat. de« Coralliaires, par MM. Milne-Edwards et J. Haime, t. ii. 

 p. 127. 



Ann. d- Marj. X. Hist. Ser. 4. Vol. \\x. 18 



