Prof. H. J. Clark on Lucernaria. 29 



Thus, in balancing the value of the organic characters of this 

 animal, we are inevitably led to the conclusion, on the one hand, 

 that Lucernaria does not stand as a totality above all other Aca- 

 lephse, nor, on the other hand, does it, by any means, belong below 

 them, and that much less does it affiliate exclusively with the 

 Gymnophthalraata. The only relation that it possibly can be 

 considered under is that of a correlation to both types of Acalephce 

 — viz. to the Gymnophthalmata, including the Siphonophora, 

 and to the Steganophthalmata — yet not as a graduated con- 

 necting link which would seem to show that the two orders pass 

 into each other, but as an ordinal type, equivalent in value to 

 either of the others, by reason of the peculiar and distinctive 

 morphology of certain of its organs. On this account Lucer- 

 naria is to be considered and may be designated as the ccenotxjpe 

 {kocvo';, common) of the Acalephse. In this respect it holds such 

 relations to the other two orders of Acalephie as do the Crinoids 

 to the other orders of Echinodermata, or the Annelidse to the 

 rest of the Articulata, or the Selachians to the true Fishes and 

 the Reptiles, at the same time, containing organic features 

 which separate each of them as a type from the others. 



In order that no confusion may arise here, I would state most 

 explicitly that I do not consider the Ctenophora as one of the 

 orders of Acalephfe, but deem them to be a class by themselves, 

 equal in value to either of the classes of Radiata, whether Polypi, 

 Acalephse, or Echinodermata, and standing next in rank to the 

 Echinodermata. The division of the alimentary system of Cte- 

 nophora into two portions, as among Polypi, is sufficient to se- 

 parate them from the Acalephse, since the typical form of the 

 corresponding system in the latter is a unity; moreover, the 

 position and peculiar relations of the tentacles of Ctenophora 

 are hardly of less importance, in these considerations, as dis- 

 tinctive characters. I cannot conceive that the Ctenophora may 

 be included in the same classitic type with the Acalephse without 

 doing violence to correlative ideas such as are expressed in the 

 organism of the former; and much less can I admit that they 

 have the most distant relation to the Polypi, excepting that, like 

 the latter, they are Radiates. The same kind of arguments that 

 have been used to show that Ctenophora and Polypi belong to 

 one class might, with equal justice, be advanced to pi'ove that 

 the Acalephse are Polypi. We must not mistake a similarity for 

 an identity, any more than that the cry of a child would identify 

 it with a cat, because their voices sound alike, and cannot always 

 be distinguished the one from the other by any single faculty of 

 our senses. 



The following tabular view presents at a glance the relations 

 of the Lucernaria to the other orders of Acalephse, and at the 



