90 Dr. F. Muller on Entoniscus Porcellanse, 



which, however, the animal moves pretty quickly from place to 

 place. The seventh segment has no feet, but bears on each side 

 at the posterior margin a wart-like process, and on this the 

 genital orifice. 



The abdomen, which is much diminished posteriorly, has no 

 appendages, as in the males of two other Bopyrida found here ; 

 the last segment is distinguished from the rest by its greater 

 length, and is beset with minute spines at the extremity. 



Of internal organs, the most striking are two wide, brownish, 

 contractile hepatic tubes, which commence csecally in the first 

 or second abdominal segment, and extend to the second thoracic 

 segment. Between these runs the intestine. Above the intes- 

 tine and liver is situated on each side a wide tubular testis, 

 which extends forward from the genital orifice already mentioned, 

 through three or four segments, and usually has an external 

 lateral diverticulum in each. The heart is seen pulsating close 

 behind the liver. 



The larvae (PL II. fig. 10) are as like those of Bopyrus as the 

 males. The flat oniscoid body is about 0'2 millim. in length, 

 and half that width ; the greatest breadth is at the second and 

 third thoracic segments, from which the body narrows posteriorly 

 to - 04 and anteriorly to 0*06 millim., the width of the nearly 

 straight frontal margin. Of the length, about 1 is occupied by the 

 head, the remainder is taken up in equal parts by the thorax 

 and abdomen, each of which is distinctly divided into six seg- 

 ments. The head bears above, near the hinder angles, two 

 roundish, black eye-spots, apparently without refractive bodies, 

 and beneath, two short, thick, biarticulate anterior antenna?, of 

 which only the terminal bristles project beyond the margin of 

 the head, and two longer posterior antennae, which spring just 

 under the eyes, and reach to the base of the abdomen; these 

 are six-jointed ; the penultimate joint and the last setiform one 

 are the longest. In the mouth, which is situated near the 

 hinder margin of the head, I could only distinguish two jaws. 

 Close to the anterior margin of the head a roundish spot, emar- 

 ginate in front, and composed of pale round granules, is seen; 

 it reminded me of the spot which is observed in the head of 

 many Amphipoda (very distinctly in the Gammarus ambulans of 

 the Pomeranian peat-bogs, and also in Leptocheirus pilosus, 

 Zadd.). 



The five anterior segments of the thorax bear similar feet, 

 originating near their margins; in these may be distinguished 

 two long cylindrical basal joints, a short third joint, a thickened, 

 ovate palm, of the length of the first basal joint, and a slightly 

 curved powerful claw, which is fully half as long as the palm. 

 In the sixth pair of feet, which does not originate so near the 



