CRUSTACEANS. 223 



§ 1. Cancerilla tubulata. — Plate LXII. figs. 1-5. 



Various reasons might be given, perhaps, and those sufficiently con- 

 vincing, for adding this animal to the list of Entomostraca, which, under 

 its present state, is rather indefinite. 



A young Ophiura, a kind of Star-fish, as above shewn, its slender 

 rays expanding about nine lines, was taken in the beginning of May, 

 Plate LXII. fig. 1. A very minute foreign object was observed affixed 

 to it a fortnight later, at the root of one of the rays, but so much inter- 

 cepted, and so indistinctly seen, that its precise form could not be deter- 

 mined. The ray, however, having Mien to pieces on the 25th of the 

 month, as incident to these animals, left the disc entire, where the ob- 

 ject was exposed as a j)rominence, fig. 2, and, on reversing the disc, it 

 appeared under the microscope, as in fig. 3, a. While clinging to the 

 mutilated disc, more of it was discovered than previously. 



This minute object proving a parasite, detached itself, when I con- 

 cluded it to be one of the Crustaceans, and probably allied to the Cancer 

 fixmily. 



The shell, rather a clumsy oval, was of dull yellow colour, bearing a 

 red cross on the centre of the back, and a red speck in front ; its form 

 rudely triangular, the margin tolerably even, with two antenna? apart from 

 each other, rough, with hairs or bristles. No eyes were visible, probably 

 from the position, nor could I find above six legs, which were armed with 

 claws. The animal fell on its back, and the legs wer-e in considerable 

 action. 



Two short cylinders, each crowned with a globular enlargement, 

 formed appendages to the body, when about twelve distinct vivid blue 

 ova could be enumerated in each of the spheres. On June 2, these 

 were so far matured, that the form of the included foetus was perceptibly 

 irregular, as exposed through the integument. In two, a red speck like 

 an eye was observed. The whole parasite might have been inscribed 

 within a circle a line in diameter. 



The parent was dead on the 5th of July, and the internal parts 

 having decayed, only the shell, with its red cross, remained. 



