298 



Stentor ; and Dr. Greef did not observe any sexual condition. 

 It is probable, as he argues^ that if sexual organs do develop, 

 the same simple form is maintained as in hydra ; and that a 

 medusoid shape is not attained by this animal. The interest 

 of this creature is great in relation to Darwinian views — and 

 especially since HaeckeFs proposition to associate the Sjionges 

 in one group with the Coelenterata. As Greef justly observes, 

 this is the simplest Coelenterate known, having no tentacles, 

 although it possesses nematophors and pigment cells. Is it 

 not rather through this form than through the Anthozoa — as 

 Haeckel wishes — that we must approach the sponges ? In 

 any case this Protohydra gives a very conclusive answer to 

 one of the objections raised against the assimilation of Sponges 

 and Coelenterata, viz., that all the Coelenterata take in their 

 food by tentacles, whilst no Sponges do so. Here is an un- 

 deniable Coelenterate with no tentacles Avhatever. Whilst we 

 are very much disposed to accept Haeckel's proposal to group 

 Sponges and what are now called Coelenterata together, as 

 Leuckart orij^inally proposed, we would be very careful not 

 to claim too close an affinity for the Sponges with the parti- 

 cular group of Corals. The development of radial septa and 

 the calcareous skeletons of the Calcispongia3 present re- 

 markable points of agreement Avith the Anthozoa, but the point 

 at which the ancestry of Sponges and Corals meets probably 

 includes within it the stock of the Hydroid polyps as well, 

 which may be supposed to have presented closer resemblances 

 to corals in the structure of their earlier representatives than 

 what we see now. 



Embryology. — Researches on the Structure and Development 

 of the Arthropoda. 4. Praniza fAnceusJ inaxillaris. 5. Pa- 

 ranthura Costana. 6. The Decapoda Loricata. With five 

 coloured plates. Koll. v. Sieb. Zcitschrift, 1st and 2nd 

 parts, 1870. — Dr. Anton Dohrn, formerly of Jena — an ardent 

 entomologist and skilful observer — has now been devoting 

 his energies for some time to the study of the develoj^ment of 

 Arthropoda, with the object of bringing facts to light bearing 

 upon the descent theory and the genetic classification of these 

 animals. He has recently been working at Naples, where he 

 intends to stay for the purpose of prosecuting these studies. 

 The contributions above named are admirable pieces of work, 

 in which the details of the embryogeny and the later develop- 

 ment of the nervous, vasciilar, and digestive systems in these 

 crustaceans is discussed. Dr. Dohrn's figures of embryos are 

 draAvn with brilliant colours, to give greater distinctness to 

 the complex disposition of parts, which hesketches diagramma- 

 tically. With such admirable workers as Dr. Dohrn and Dr. 



