ACALEPHAi.

531

minori, quam altera, tetraedra, apice rotundato; lobis latis-simis, cavitatis natatorise marginem superantibus; cavitatenutritoria minima, processu posteriore petiolato, multomajore.

As Irish Acalephse, there are noticed by Thompson(Annals Nat. Hist, xiii, 1844, p. 440) Cydippe pileus, Meli-certum campanulatnm, Aurelia aurita, bilobata, and CyaneaLamar ckii.

Physophora tetrasticha has been more particularly de-scribed by Philippi. (Muller’s Arch. 1843, p. 58.) Fourrows of cartilaginous swimming-vesicles may be distin-guished at its axis, beneath which is placed a doublecircle of prehensile tentacles. The exterior tentacles, ofwhich there are from sixteen to twenty, are considered byPhilippi as true prehensile tentacles (Fangarme). Theinterior tentacles consist of three portions, viz. : of a globosebase with granular contents, upon which is placed a ventri-cose middle portion, with a narrow-pointed terminal piece.From the basal portion of these tentacles filaments hangdown, which are beset with shortly-pedunculate, elliptical,and spirally striated corpuscles. The hollow axis projectingabove the swimming-vesicles contains no air, and presentsinteriorly, among the tentacles, an aperture, which is pro-bably the oral orifice. Moreover, among the tentaclesthere are also some free cluster-shaped organs, of which ashort cluster is always associated with a long one; theyprobably represent an ovarium and testis. Philippi hasalso expressed himself with regard to the distinction of theearlier species of Physophora described by Peron, Forskal ,and others. Kolliker (Froriep’s n. Notiz. Nr. 534, p. 81)has communicated his observations on the marginal bodiesof various Pulmograda, which have led him to regard thecorpuscles furnished with a pigment as analogous to theeyes, and, on the other hand, those without pigment, to theauditory organs. Hollard would be inclined to regard theAcalephre allied to Porpita and Velella as a small naturalfamily, or rather, perhaps, as a distinct order, and asks