74 TOMOPTERIDiE. 



loose skin, which corrugates into folds. Eyes two, black, small, on 

 the summit of the head, between the posterior lobes : a line of 

 minute black specks runs down the middle of the neck behind the 

 eyes. Body narrow at each extremity, widening in the middle, fur- 

 nished on each side with sixteen fin-like narrow lobes, each of which 

 bears at its extremity two oval branchial ? leaves set on obliquely. 

 The ultimate pairs diminish gradually, and are succeeded by a few 

 pairs of rudimentary processes on each side of a slender tail. Vis- 

 cera : — a simple, clear, rather wide canal running through the whole 

 length, ordinarily parallel-sided, but sometimes constricted so as to 

 form a succession of spindle-shaped divisions, which pass from the 

 head to the tail in rather slow pulsations, like the dorsal vessel of a 

 caterpillar. A thick oesophageal proboscis was once protruded from 

 the mouth, of an obconic form, with a large somewhat four-sided 

 orifice obliquely terminal. No other internal structure was visible, 

 notwithstanding the perfect transparency of the animal." 



" Three specimens of the Johnstonella have come into my posses- 

 sion, all of which were dipped from the surface of the sea oif the 

 harbour of Ilfracombe, about the end of August. In a glass jar 

 their motions were excessively vivacious ; they swam with great 

 swiftness by the rapid vibration of the lateral fins ; so incessantly, 

 that it was with the utmost difficulty I could examine them with the 

 microscope. They darted through the water in all directions, across 

 and around the jar ; and when they rested, their translucency ren- 

 dered them almost invisible. They soon died in captivity ; I thmk 

 I did not keep one of them longer than the second day." — P. H. 

 Gosse. 



" The animal described by Mr. Gosse under the name of Johnsto- 

 nella Catharina appears to belong to the same genus as the animal 

 described by Eschscholtz in the * Isis ' (1825), p. 736. t. 5. f. 5, under 

 the name of Tomopteris onisciformis from the South Seas ; and by 

 MM. Quoy and Gaimard in the * Voyage of the Astrolabe,' ii. p. 284. 

 t. 21. f. 21, 24, under the name of Briarcea Scolopendra from the 

 coast of Spain. Hermannsen has proposed to change the latter 

 name to Briarcea : Harry Goodsir calls it Briareus : and Mr. R. Ball 

 writes it Bryarea. Eschscholtz and Quoy and Gaimard regard it as 

 a moUusk ; the first referring it to the order Heteropoday and the 

 latter to the Nudihranchiata. 



"Mr. Harry Goodsir, who found the animal abundant in the 

 North Sea (Ann. and Mag. Nat. Hist. 184.5, xvi. 163)," observing 

 the presence of ** cilia fringing the bifurcated posteriors of the lateral 

 extremity of its body," decided that it could not be a mollusk. 



" Menke (Zeitschr. fiir Malac. 1844, p. 21) proposes to remove the 

 genus to the Annelides ; more recent authors have considered it as a 

 Crustacean. 



" Mr. Gosse at first sight thought it might be a Brachiopod Crus- 

 tacean, but thinks it has more affinity to the Annelides (p. 348), and 

 refers it to that class in the Systematic Index. 



" According to Eschscholtz and Quoy and Gaimard, the South Sea 

 specimens are very much smaller than those found in the Mediter- 



