6 Dr. G. Dickie on the Marine AlgcB 



starting movement like that of a full-grown Sagitta. At the ante- 

 rior extremity, near the head, a pulsating organ can be distinctly 

 seen. The ovum in all these stages contains a minute globule, 

 which causes it to float on the surface of the water, and appa- 

 rently is formed of air : I presume that it is the same globule with 

 that seen in the e^^y when first released from the ovary. The 

 change in the floating ova from the state in which the inner 

 sphere consists of granular matter without any trace of a young 

 animal to the succeeding states must be rapid ; for on the 27th 

 of September all the ova were in this first state, whilst on the 

 29th the majority contained partially developed young ones. 

 These floating ova were y^^^ ^^ ^^ ^^^ ^^ diameter, whereas the 

 spherical balls of granular matter which I saw expelled from their 

 pointed oval cases were barely the jq th of an inch in diameter ; 

 but as the eggs within the ovaries were of difi'erent sizes, accord- 

 ing to their states of maturity, we might expect that their growth 

 would continue after having been expelled from them. I will 

 conclude by expressing a hope that these few observations on the 

 propagation of this curious genus may aid more competent judges 

 than myself in ascertaining its true aflinities. 



EXPLANATION OF PLATE L 

 L Intestinal tube. 

 o o. Ovaries. 



A A. Apertures of the ovaries, and lateral fins. 



T T. Tail divided into four columns of circulating granular matter, the 

 course of which is shown by the arrows. 



B. Egg just liberated from the ovary. 



C. Egg in first state of change. 



D. Egg in a succeeding state. 



II. — On the Marine Algce of the vicinity of Aberdeen. By G. 

 Dickie, M.D., Lecturer on Botany in the University and 

 King^s College of Aberdeen. 



[With a Plate.] 



In the present and subsequent communications it is proposed to 

 enumerate the marine Algse which have been found in the vicinity 

 of Aberdeen, and also to record such observations on their struc- 

 ture as may seem of most interest. 



Although no great merit attaches to mere local lists, still such 

 are not to be entirely rejected as useless, more especially when we 

 consider their utility to those whose attention is directed to the 

 geographical distribution of plants, a very interesting and im- 

 portant branch of their history. 



All the species to be mentioned have been collected on the 

 Kincardineshire coast, the southern part of the Aberdeenshire 



