424 
physiognomy, would, in the first instance, suggest. The form, 
on the other hand, of the accessory oral organs, or maxillary 
feet, which are here constructed so as to constitute organs of 
attachment, as well as the singular development of the dorsal 
arch of the posterior thoracic ring, and the connexion of the 
feet of opposite sides, through the intervention of a large in- 
tercoxal plate,—a striking feature in the greater number of the 
suctorial crustacea, but not found in the true entomostraca,— 
unite with the semi-parasitical habits of Notodelphys in indi- 
eating an affinity not to be mistaken with the true suctorial 
tribes. 
Dr. Allman read another paper on a new Genus and Spe- 
cies of T'racheary Arachnidans. 
In this paper the author described a Tracheary arachnidan 
discovered by Dr. O’Brien Bellingham in the posterior nares 
of a seal (Halicherus gryphus). It turns out, on examination, 
to be generally distinct from all the forms hitherto on record, 
and Dr. Allman assigned to it the appellation of Halarachne 
Halicheri, with the following generic characters : 
HaALaRaAcHNE,* Mihi. 
Gen. Cha.—Palps free, filiform; mandibles didactyle ; 
sternal lip, bifid ; Zegs with the last joint terminated by two 
hooks, and an intermediate three-lobed caruncle; body entire, 
elongated, sub-cylindrical, furnished anteriorly with a dorsal 
plate; eyes, none. 
Species unica.—H. Halicheri. Hab.—Infesting the pos- 
terior nares of Halicherus gryphus, Irish coast. 
H. Halicheri possesses a very distinct tracheary system, 
opening externally by means of two spiracles, which are placed 
one at each side of the anterior extremity of the abdomen. 
The alimentary canal, just before its termination at the pos- 
“From dXc, mare, and apayyn, aranea. 
