ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 965 



plained by the presence of a hard, inflexible, calcareous exoskeleton, 

 while the possibility of better nourishment in the endoderm should be 

 taken into consideration. 



There is no good reason for associating Millepora with Hydractinia in 

 the zoological system ; the Milleporidee and Stylasterid^e probably 

 belong to a separate stock altogether from the Hydromedusfe, and to one 

 which never possessed medusse or medusiform gonophores. 



Larval Actiniae parasitic on Hydromedusse.* — Prof. A. C. Haddon 

 has a note on some parasitic larval Actinias found at St. Andrews by 

 Prof. M'Intosh. At first sight, these larvae appear to be young of 

 Halcampa chrysanthellum, but they differ in the much less conspicuous 

 longitudinal retractt)r muscle of the larger tentacles ; it may be that 

 Prof. M'Intosh was right in regarding them as young specimens of 

 Peachia Tiastata. 



Scyphistomata of Acraspedote Medusae.f — Dr. P. Fischer gives a 

 short account of some Scyphistoma-forms which he examined at KoscoflP, 

 and which, though kept under observation for ten days, exhibited no 

 signs of strobilization. A number of explanations, more or less satis- 

 factory, suggested themselves to him. 



(1) They were primitive, and ought consequently soon to produce 

 Ephyree ; against this we have the observation that they did not do so. 



(2) They constituted the remnants of primitive Scyphistomata after 

 the departure of the Ephyrae. On these residual forms a new colony 

 would be developed, which might strobilate in the succeeding spring. 

 As to this it can only be said that we have as yet no information as 

 to the fate of the remains of the Scyphistoma-larv® after the formation 

 and departure of the Ephyrae. 



(3) They were primitive, but born late, and so had to retain their 

 actiniiform stage until the succeeding spring. Here, again, we know 

 little as to the influence of the date of birth on the further development 

 of Scyphistoma. 



(4) They arose from an acraspedote Medusa which does not strobilate, 

 but passes at once into the Ephyra-stage ; but the iiTegularity of the 

 numbers of their tentacles is against this view. 



Supplementary Report on 'Challenger' Actiniaria.|— Prof. E. 

 Hertwig has a second report on the Actiniaria collected by the ' Chal- 

 lenger,' which affords him an opportunity for making some critical 

 observations on Andres' monograph of the group. A good deal of the 

 more interesting part of this report is contained in the extracts from 

 Dr. Erdmann's investigations into the anatomy of the Zoantheae, which 

 we have already noticed.§ 



Porifera. 



Boring Clionids.|l — M. Nassonoff has investigated several species of 

 Clionids, and especially a new species, C. stationis Nass., which lives on 



* Ann. and Mag. Nat. Hist,, ii. (1888) pp. 2.56-9. 



t Bull. Soc. Zool. France, xiii. (1888) pp. 96-9. 



i ' Challenojer' Eeports, Ixxiii. (1888) 56 pp. (4 pis.). 



§ See this Journal, 1886, p. 454. 



II Arch. Slav. Biol., iv. (1888) pp. 362-6. Bull. Soc. Nat. Moscou, 1. (1888) p. 236. 



