﻿Scientific InisUigence. 156 



cation does exist between the organs and the surrounding me- 

 dium, it is by means of simple oritices in the walls of the cavity." 

 The " depuratory apparatus" of "Vermes" is so diverse in 

 structure and position in the different groups, as to render it 

 very questionable whether these organs are homologous in the dif- 

 ferent orders. Moreover, there is still so much to learn concern- 

 ing both the proper vascular circulation and the " depuratory 

 apparatus" of ordinary Mollusca, and the connection of both with 

 the exterior, that it is very unsafe to base generalizations on neg- 

 ative evidence of this kind. Even now, the utmost diversity of 

 opinion exists, among the leading European anatomists, concern- 

 ing the character of these organs in the commonest JMollusks, some 

 asserting and others denying the existence of external vascular 

 connections, lacunpe, capillaries, etc. It should also be considered 

 that no " segmental organs" have yet been detected in the nearest 

 allies of the Annelids, the Crustacea, although the two classes 

 agree so closely in nearly all other respects that no one has been 

 able, as yet, to frame strictly distinctive diagnoses for them. 

 Nevertheless, the existence of the infundibuliform organs in Brach- 

 iopods is certainly one of their most remarkable characters ; and 

 also one of the strongest analogies with the Annelids which they 

 possess. 



The character of the nervous system of Brachiopods, according 

 to the author's own statements, is quite as much like that of a 

 degraded mollusk as like that of a degraded worm, and has no 

 special resemblance whatever to that of any of the true Annelids, 

 with which the author wishes to compare them. We may as well 

 compare it with the nervous system of a Lamellibranch, without 

 the pedal and posterior ganglia (for which there is no use), as 

 with that of an Annelid destitute of the ventral series of ganglia. 

 "In the Annulata, with the exception of the Discophora, the 

 generative products are set free in the perivisceral cavity, receiv- 

 ing from the fluid therein contained certain nourishment." An- 

 other notable exception is found in the common earth-worms, and 

 their allies, which have a distinct oviduct and male organ, in the 

 median line beneath, and, like many leeches, lay eggs enclosed in 

 capsules, not unlike those of many mollusks. Other exceptions 

 also occur in the Annelids, while among the Cestodes, Trematodes, 

 Nematodes, and Turbellaria, the oviduct is usually single and 

 connected directly with the ovary, as in most Mollusca. But in 

 Polyps and many common Fishes, etc., the generative products 

 are discharged into the perivisceral cavity, as in most Ch?etopod 

 Annelids. This is obviously a character of small importance, 

 hardly sufficient to characterize even the several orders of Aime- 

 lids. In the Mollusca, "with the exception of the Octopoda, the 

 oviduct is single." Many other exceptions occur, in the Chitons, 

 Lamellibranchs, etc. " Among the Mollusks, even when devoid of 

 a shell in the adult, the embryo early develops a shell composed of 

 one or two pieces." This is not the case in many Cephalopods 

 and Pteropods. 



