Chap. II. 



AURELIA FLAVIDULA. 



27 



The double border of the lips in PI. X". Fig. 5 c is produced by the over- 

 lappiug of the edge of the outer or upper wall upon the inner or lower waU. 

 In Fig. 1, the inner wall having brought together its edges, excepting around a 

 veiy small area, e, the cruciate mouth appears to be veiled by a thin membrane 

 which has a central perforation, c, whilst the upper or outer wall is rendered 

 conspicuous at its eight edges by numerous thickly crowded lasso-cells. At c in 

 Fifj. 4"" the relative thickness of these two walls, as they stand out in profile, is 

 very clearly shown. The lasso-cells are not so uniformly disposed over the body 

 as in the last phase, but beside being generally diffused, they are crowded at the 

 borders of the mouth {Fig. 1 c), and grouped in semi-globular masses («^ «^) on 

 the tentacles. When the tentacle is contracted {^Fig. 3), the lasso-cells («^ a-) appear 



cates of the double wall of the velum, -wliioh jiro- 

 jects from the bell in the form of a four-sided 

 pyramid. The fact that the medusa is fixed by a 

 pedicel to rocks and shells does not invalidate our 

 assertion, for we have on our own coast the genus 

 Eliizogeton (PI. XX. Figs. 17-23), which bears 

 its medusM on the stolons which run over the rocks. 

 Now, it is possible that Steenstrup overlooked the 

 connection of the medusa with a stolon, and, if the 

 hydroid form was present, supposed that it was 

 another animal, or perhaps the hydroid had been 

 resorbed, as often occurs in Coryne (PI. XVII. 

 F'kjs. 13, 14, and 1.5), and nothing but the medusa 

 form is left standing, mouth upward, on the stem 

 (PI. XVII. Fig. 1.5). "We would seem to be borne 

 out in the belief that Steenstrup's scyphostoma is 

 a Turris, from what Dr. Wright (Edinburgh New 

 Phil. Jour. vol. 10, 1859, p. 105, PI. VIII. Fig. 1) 

 has observed on the shores of Scotland. He 

 collected the eggs of Turris neglecta and reared 

 the young until they developed into Hydroids, which, 

 both in size and zoological features, closely resem- 

 ble, if they are not generically identical with, our 

 Illiizogeton. At any rate, we cannot doubt that 

 Steenstrup's figures do not represent a scyphos- 

 toma, but a naked-eyed Medusa, if not the genus 

 Turris; and therefore we are surprised to see that 

 Sars ("Fauna Littoralis Norvegia;, 184G, p. 14") 

 says, " Steenstrup, more fortunate than I, has found 

 in the Medusa-nurses a vascular system (Gefass- 

 systeni) (of which I had noticed only the four 

 i-adiating canals, which appeared to me like swell- 



ings), and in the bottom of the bell a tubuliform 

 stomach or mouth." At this time Sars was con- 

 versant with several forms of naked-eyed Medusa?, 

 as his figures show ; and yet he overlooks the simi- 

 lar nature of Steenstrup's so-called scyphostoma. 

 In the Ann. and Mag. Nat. Hist. 1848, vol. 1, p. 

 25, PI. v., Dr. Reid describes the genuine scy- 

 phostoma of Aurelia, which he obtained on the 

 shores of Scotland, and identifies it with the animal 

 of SteenstruiJ. Under this impression he jsroceeds 

 to argue that Steenstrup could not have seen any 

 canals in the pyramidal projection of the lips, 

 because he does not in the Scottish animal ; but 

 he represents the four longitudinal ridges in the 

 digestive cavity of scyphostoma as hollow, and, 

 moreover, asserts that they " terminate at their 

 upper end in another canal, encircling the mouth 

 and placed between it and the margin of the disk,'^ 

 p. 27, Fig. G b. But we most positively assert 

 that these longitudinal ridges are not hollow, nor 

 is there the least trace of a circular canal in which 

 the ridges are said to terminate. — Frantzius 

 (Siebold und KoUiker Zeitschrift, 1853, Bd. 4, p. 

 120, PI. VIII. Figs. 1-4) also indorses Steenstrup's 

 mistake, and describes, in the scyphostoma of Cephea 

 borbonica, what he considers to be the homologues 

 of the radiating canals of the bell ; but, unlike Reid, 

 he could not persuade himself " that these canals 

 really emptied into a circular canal at the base 

 of the tentacles." What is remarkable, he repre- 

 sents these canals in his figures as if they were 

 situated in the outer wall of the body. 



