ON THE REPRODUCTIVE SYSTEM IN THE HYDROIDA. 351 
Parricuars or Tria Tries. (Table A.) 
Banshee. Llewellyn. Victoria and Albert. Leinster. Connaught. 
Bees sce 10th Jan., 1848) 15th May, 1848/23rd July, 1855 |26th July, 1860/27th Sept., 1860 
ied......... Long Reach |NoreandMonuse| Stokes Bay Stokes Bay Stokes Bay 
pare 8 ft. Sin. 8 ft. Gin. 13 ft. 10in. | 12 ft. 22in. 12 ft. 9in. 
aa 9 ft. 9 ft. Qin. 14 ft. 13 ft. 23 in. 13 ft. Qin. 
192 ft. 185 ft. 401 ft. 336 ft. 341 ft. 
rolutior 30°5 28°5 25-4 26°25 mean 25:5 
| 19 Ibs. 20 Ibs. 231bs. _|25 Ibs. by gauge|264 Ibs. by gauge 
; | an as 25 in. 25 in. 252 in. 
350 350 600 720 720 
1,555 1,890 2,980 4,751 4,735 
a. 161 15912 | 16-837 17-747* 18-079* 
Statute Miles.) 18-553 18-317 19-377 20:429 20'811 
Report on the present State of our Knowledge of the Reproductive System 
im the Hydroida. By Geo. J. Atuman, M.D., F.R.C.S.I., F.R.S., 
F.RS.E., M.R.IA., Regius Professor of Natural History in the 
University of Edinburgh. 
From the time that Ehrenberg announced a sexual differentiation among the 
_Hyprorma, and assigned a significance which was very nearly the true one to 
_ those parts of their structure which are at present known to be destined for 
the formation of ova and spermatozoa, a marked progress set in in our know- 
Biedze of the phenomena, morphological and physiological, which occur among 
_ these animals ; and the investigations of numerous observers, both in this 
country and abroad, have thus resulted in a very extensive, if not yet com- 
plete, acquaintance with a group of animals which are probably not surpassed 
_ by any in interest, whether we regard the singularity and beauty of their 
forms or the light which they seem capable of throwing upon various questions 
in morphology and physiology,—a group, however, which, if we would hope 
| to attain to any important knowledge of the structure, functions, and rela- 
tions of the animals which compose it, can alone be studied by laborious ob- 
_Servation of these animals in their living state, and by unremitting and 
_Wearying microscopical dissections, while even this would lose half its value 
“unless accompanied by faithful drawings, as the only means by which it is 
bossible to give permanence to the characters of these frail and transitory 
ganisms. 
z, Many years’ study of the Hyprora has, however, convinced me that the 
Ri ecomens of their life-history have not all received their true interpretation ; , 
___ * The mean of four runs. 
__ ¢ The greater part of the following Report was laid before the Cambridge Meeting of 
he Association, in Sept. 1862; it was only, however, at the following Meeting, August 
1863, that it was possible to present it in ils completed form. 
