M. Valenciennes on the Gorgonidse. 177 



chamber is smaller than the middle, and this than the anterior 

 one. The latter is very considerably enlarged immediately be- 

 hind the above-mentioned tubercle, and is no doubt m free 

 communication with the cavity of the body or the interstices 

 Uacurue) between the organs, and this is very probably the case 

 also with the hinder chamber. In the bottom of each notch 

 there is an opening for the entrance of the returning blood, so 

 that there are four such apertures, arranged m pairs. From 

 this description it is evident that the heart of the Pycnogouidie 

 agrees essentially in form and structure witli that ot the higher 



Arachnida. . , 



The circulation goes on pretty rapidly m a distinctly marked 

 course, and if the nutritive tluid contains a sufficient quantity 

 of blood-corpuscles, may be easily observed. The chambers ot 

 the heart contract simultaneously. At each diastole, the blood 

 returning from the organs is taken up by the heart through the 

 four lateral openings and driven forwards at each systole. In 

 this manner a small portion of the blood reaches the proboscis, 

 whilst the greater part takes its course in the form of a consi- 

 derable stream towards the abdomen. From this principal cur- 

 rent, lateral streams are given off to the legs; these pass down 

 one side of the respective legs and up the otner, so as to return 



at last to the heart. ^ i , i i 



In conclusion I must remark, that \ an Beneden has already 

 observed a regular circulation of the blood in the legs of Nym- 

 phon^. He could not discover the heart, and according to him, 

 the Impulse is given to this current of blood m the extremities 

 by a peculiar, rhythmically contractile membrane, situated withm 

 the base of the legs. But as it is now certain that the blood 

 circulates in all parts of the body by the action of the heart 

 alone, we may very justly doubt the existence of any such ar- 

 rangement as this in the legs of the Pycnogonidse. 



EXPLANATION OF PLATE VIL 

 Fiq 7 Sketch of the heart of Pkoxichilus. The numbers 1-4 indicate 

 the several thoracic segments ; a, proboscis ; b, abdomen ; c, the 

 four eyes ; d, d, d, d, the legs ; e, e, the stomach with its lateral 

 cieca ; /, intestine ; g, the anterior, h, the middle, and i, the 

 hinder chamber of the heart ; l, k, the constrictions of the heart. 



Wl.— Abstract of a Monograph of the Family Gorgonidfc. 

 By M. Valenciennes. 



M. Milne-Edwards has shown that the animals of the class 



of Polypes belong to two great orders. One of these, called 



Anthozoa (Zoanthaires), includes those animals which more or 



* Froriep's Notizen, xxxvii. p. 7^- 



