A HISTORY OF ESSEX 



is that few kinds of animals can establish themselves permanently, which 

 is very unlike what occurs in other tidal estuaries in the county. 



TABLE IV 



Mean of all per 10 gallons 



6-6 



I. PROTOZOA 



Noctiluca mlliaris. 



This varies greatly in numbers at different 

 places and in different seasons. Sometimes 

 there are few, but on one occasion I found 

 that the average number in the water of 

 Harwich harbour, from the surface to the 

 bottom, was about 4,000 per gallon. 



II. PORIFERA (Sponges) 



The best locality in the county seems to be 

 the creeks east of Walton-on-Naze. The 

 following species have been identified, but 

 probably others occur, which have been ob- 

 tained in the Orwell. 



I. CALCAREA 



1. Leucosolenia lacunosa, Johnston. 

 Dredged in the Wallet by Mr. H. W. 



Unthank. 



2. Leucosolenia botryoides, Ellis & Sol. 



Pin Mill on the Orwell ; also dredged in 

 the Wallet by Mr. Unthank. 



3. Sycon coronatum, Ellis & Sol. 



In the creek east of Walton-on-Naze and 

 in the Colne. Mr. Unthank records it from 

 the Wallet. 



4. Sycon compressum, Auctt. 



The only place in the county where I have 

 found this species is in the creek east of 

 Walton-on-Naze. 



II. SILICEA 



I. Cbalina oculata, Pallas. 



Possibly all my preserved specimens have 

 been collected just outside Essex, but it is 

 almost certain that it occurs at Harwich and 

 Walton. 



2. Halichtmdria panicea, Pallas. 



This occurs in the Colne, but not abund- 

 antly, and I think I have seen it near Harwich 

 and at Walton. 



3. Isodictya fucorum (Bowerbank). 

 Dredged in the Wallet by Mr. Unthank. 



4. Isodictya palmata ? (Bowerbank). 

 Dredged in the Wallet by Mr. Unthank. 



5. C liana celata (Grant). 



This sponge does some injury to the 

 oysters. My friend, the late Mr. Fred. 

 Wiseman, told me he had found that by 

 keeping the shells dry for a time the sponges 

 could be killed, and the oysters restored to a 

 healthy state. 



I have found several other species not yet 

 identified, and probably many more occur, 

 since some seem to be very local, and not to 

 be met with every year. 



III. CCELENTERATA 



(Jellyfish, Sea Anemones, etc.} 



I. HYDROZOA 

 i. HYDROID ZOOPHYTES 



I have never made any effort to collect 

 the more minute species, and the list would 

 have been much more incomplete than it is 

 if Mr. Wm. Cole had not lent me a collection 

 made by Mr. Hope near Harwich, the species 

 of which are distinguished by his name. They 

 have been identified by Mr. Walter Garstang. 



1. Coryne vaginata, Hincks. 



Taken by Mr. S. P. Hope in Essex waters 

 near Harwich in June and July. 



2. Syncoryne eximia. 



Off Brightlingsea (H. W. Unthank). 



76 



