428 EEVIEWS. 



like Milne Edwards, lie regarded it as the sole representative of a 

 primary division of this group, for which he proposes the name of 

 Cylicozoa. 49 And this opinion he appears still to hold. But the 

 question as to the Medusan affinities of the Lucernariadae was 

 not permitted to rest. In 1856, Professor Huxley 50 again dis- 

 cussed their close resemblance in structure to the Discophora 

 Phanerocarpse of Eschscholtz, more particularly to those so-called 

 larval forms of this group, which, since the appearance of Dalyell's 

 work, have become familiar in elementary treatises under the name 

 of Hydrce tubed. In both Lucemaria and Hydra-tuba a true digestive 

 zooid, or polypite, is seen to project from the centre of the free 

 extremity of the animal. In both, likewise, this polypite is surrounded 

 by a variously-shaped cup or disc, bearing the marginal tentacles, 

 and formed by an expansion of the body-wall, homologous with the 

 natatorial organ, or umbrella, so conspicuous in most "jelly-fishes." 

 Again : the space intervening between this umbrella and the sides of 

 the central polypite is, both in Lucemaria and Hydra-tuba, divided 

 into a number of sinuses, which must by no means be confounded 

 with the body-chambers of Actinia, seeing that the partitions which 

 separate them present an anatomical arrangement very different to 

 that of the mesenteries in the last-mentioned genus and its allies. 

 And, in both genera, the position of the reproductive organs is 

 strikingly dissimilar ; for while, in Lucemaria, they are lodged within 

 four equi-distant folds, which descend along the body of the polypite, 

 in Actinia, as is well known, they are situate below the gastric sac, 

 on the free edges of numerous mesenteric plates. 51 Gruided by these 

 considerations, Professor Huxley suggested the union of the Lucer- 

 nariadae and Phanerocarpse into a single order, bearing the name of 



49 Or Beclierpolypen. See his essay — Ueber die Morphologie und die Ver- 

 wandtschaftsverhaltnisse der wirbellosen Thiere, 1848, p. 20. The name he after- 

 wards changed to Calycozoa. Leuckart, who includes the Sponges among the 

 Polypi, divides this class into three groups, Calycozoa, Anthozoa, and Porifera. 

 (Vid. Bericht in Wiegmann's Arch.) 



50 Lectures (sup. cit.), pp. 566-7, June 7, 1856. 



51 In a valuable memoir by Professor Allman on the structure of Carduella, 

 (Q. J. M. S. I860), a genus closely allied to and previously confounded with Lucer- 

 naria proper, the precise relations of the body-partitions, polypite, and reproductive 

 organs are very carefully illustrated aud described. Professor Allman, however, is 

 of opinion that the Lucerriariadsa rank nearer to the Gymnophthalmatous (Crypto- 

 carpse) than to the Steganophthalmatous division of the Discophora. But those 

 parts of the umbrella in Carduella which he considers to be the homologues of the 

 nectocalycine veil of the Cryptocarpae, namely, the marginal lobes reflected inwards 

 so as to roof in its four outer canals, ought surely to be rather regarded as corre- 

 sponding with structures of a like nature, surrounding the open edge of the disc in 

 many free-swimming forms of Phanerocarpa?. The development of the umbrella of 

 Lucemaria has not yet, it is true, been made the subject of direct observation, but 

 its structural identity with what appears to be the corresponding organ in Hydra- 

 tuba, whose development is so well known, leaves little room for doubt that the one 

 is indeed homologous with the other, both being alike dissimilar to the swimming- 

 bell of the Cryptocarpae, the formation of which takes place in so obviously different 

 a manner. 



