Chap. II. CLASSIFICATIONS OF ACALEPHS. 147 



The contributions; of Kolliker to the natural history of the Acalephs are as 

 varied as they are important, though sometimes consisting simply of short notices. 

 A report of the investigations made by him in Messina, in connection with 

 Gegenbaur and H. Miiller, and published in the "Zeitschrift fur wissenschaftliche 

 Zoologie," vol. 4, p. 299, contains a vast amount of information upon the Acalephs 

 of the Mediterranean. In his larger work on SiphonophorcT?, "Die Schwimmpolypen 

 von Messina," however, he has not only given a very full account of the species 

 he observed in Messina, including new genera and the characteristics of new families, 

 but he has also published a diagram of his views respecting the affinities of the 

 lower animals generally, as follows : — 



CLASSIFICATION OF KOLLIKER, 18.53. 



The members of the class of Acalephs are so combinea with the Polyps and Bryozoa by Kolliker, 

 that his views respecting their affinities can only be appreciated by a comparative study of his whole 

 diagram of tlie Radiates with other classifications of the Invertebrates generally. He divides the Radiata 

 in the following manner : — 



I. RADIATA MOLLUSCOIDEA. 



1st Group. Hydkoidea. A. Hydroidea sessiUa: Hydra. 



B. Hydroidea nechalea: Physophora, Diphyes, Athorybia, etc. 

 2d Group. HvDROJiEDUSlDA : Coryne, Sertularia, Tubularia, Vclella, and Gymnopthalmata : Oceania, 



Bougainvillea, etc. 

 3d Group. DiscoPHORA : Steganophthalmata : Medusa, Rhizostoma, Cephaea. 

 4th Group. Ctenophora. 

 5th Group. Anthozoa. 

 Cth Group. Bryozoa. 



II. R.ADIATA ECIIINODERMATA. 



1st Group. HoLOTHURiDA. — 2d Group. Echisida. — 3d Group. Asterida. — 4th Group. Crinoidea. 



Kolliker thus coincides with Leuckart in separating the Echinoderms from the Polyps and Acalephs 

 as a primary group of the animal kingdom, and uniting the minor sections of the two latter classes into 

 another great division. Disregarding, however, all the categories of the system of Zoology by which animals 

 may be divided into classes and orders, he divides the Hydroidea nechalea, which he calls also Polypi 

 nechalei, into five famihes : — 



1st Family. Physophoridai : Forskalia, Agalmopsis, Apolemia, — Physophora, — Athorybia. 



'2d Family. Hippopodiida; : Ilippopodius, Vogtia. 



3d Family. Pray id a; : Praya. 



4th Family. Diphyidre : Diphyes, Abyla. 



5th Family. Velellid;e : Velella, Porpita. 



Though Leuckart has not published a general classification of the Acalephs, he 

 has done so much for the advancement of the natural history of that class of 



