532 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Polyphyidse, and has some points of structural resemblance to the 

 Phjsophoridse. 



Passing from the Calycophoridse to the Physophoridse, the author 

 points out the many resemblances which connect the two orders. In 

 the embryos of both a heteromorphous rudimentary nectocalyx is formed, 

 which is lost in most if not all Calycophoridse, while in the Physo- 

 phoridse it becomes converted into the pneumatophore. In the more 

 highly organized Calycophoridae there are a number of calyces of the 

 same form, the close concentration of the buds into Eudoxia-groups is 

 given up, and in some species the stem is transformed, as in many 

 Physophoridee, into a gemmiparons disc. Here, then, we have a series of 

 characters which seem to indicate that the Physophoridse took their 

 origin, if not from the Stephanophyidse or Polyphyidse, at least from a 

 root common to the two orders. Stephanopliyes with its heteromorphous 

 tentacles shadows forth a condition which has hitherto been regarded as 

 an exclusive characteristic of the Physophoridse. 



The morphology of Halistemma pactum has been closely examined, 

 and it is shown that the order of gemmation is regular ; the author 

 leaves it to Prof. Haeckel to reconcile this fact with his theory of the 

 multiplication and dislocation of the medusa-organ on the Siphonophoran 

 stock. In the post-embryonic development of Crystallodes rigidum a 

 point of great interest is the peculiar formation of the larval tentacles. 

 Haeckel thinks that the cnidaria of the primary tentacle are directly 

 developed into the definitive cnidaria. Observation, however, has shown 

 that they are larval structures, which, later on, are succeeded by hetero- 

 morphous organs. The nectostyles of some gigantic examples of 

 ForsJcalia ophiura were a foot in length. 



New Athorybia.* — Mr. J. Walter Fewkes describes Aihoryhia cali- 

 fornica sp. n., which differs from any known species in the form of its 

 tentacular knobs. The sacculus, which ordinarily forms a bell-shaped 

 covering, is much modified and reduced in size; it is a globular or 

 hemispherical enlargement which shows the spongy cellular walls which 

 have been described in the knobs of the genus Bhizophysa. If the 

 question were raised as to whether this new form was not the young of 

 some long-stemmed Physophore, like Agalma, the author confesses that 

 it may be so. But if larval, this new form is different from any larva 

 yet described. The sexual bodies are but little developed, and, even if 

 they were well so, that fact alone would not prove the maturity of the 

 animal, for among the Physophores there are known genera in which the 

 sexual products are matured before the adult form is reached. 



Eyes of Acalephge.t — Herr W. Schewiakoff has examined the eyes 

 of several Acalephse. He finds that there is great diversity of structure, 

 and that they are so far genetically connected that the simpler only 

 represent developmental stages of such as are more highly organized. 

 In the simplest cases the eyes have the form of a pigment-spot, as in 

 Aurelia aurita. These spots are formed of cells, the pigment- and 

 the optic-cells, with two different functions, which are performed in 

 definite areas of the ectoderm, the so-called sensory epithelium. These 

 are the districts from which the light-perceiving spots are developed. 



The next step in the further complication of the optic organ consists 



* Ann. and Mag. Nat. Hist., iii. (1889) pp. 207-10 (1 pi.). 

 t Morphol. Jahib., xv. (1889) pp. 21-60 ^3 pis.) 



