STRUCTURE OF LERNEOPODA DALMANNI. 88 



ment, close to the posterior margin. The orifice is supported by chitinic bands. The 

 cement organ consists of a simple delicate tube. It commences in the anterior 

 part of the abdomen, and passes backwards close to the lateral wall. Its posi- 

 tion may be frequently recognised through the integument without dissection, 

 especially in the living animal. It joins the ovarian duct close to the genital 

 orifice. In all the animals we examined the ovaries were distended with ova. 

 They formed opaque, white masses, readily seen through the semi-transparent 

 integument of the abdomen. 



The ova-strings are xVths of an inch long, cylindrical in form, of greater circum- 

 ference at their attached than free ends. They are slightly curved, the con- 

 cavities being directed inwards. The ova lie in longitudinal rows, with a spiral 

 tendency. When a transverse section is made through an ova-string, the ova at 

 the periphery are seen to be very elongated, whilst those in the centre are nearly 

 circular. When the ova-strings rupture, in order that the ova may be discharged, 

 they burst along the inner concave aspect. The margins along the line of rupture 

 become everted, and thus the exposure of the ova in the interior of the string is 

 facilitated. 



The animal possesses a very powerful muscular system. The largest bands 

 are situated on either side of the dorsal and ventral mesial lines, being attached 

 to folds of the chitinic integument. The buccal apparatus, antennae, and arms, 

 have special muscular arrangements. In many, of our dissections the complex 

 structure of striped muscular fibre was very beautifully illustrated. Resolution 

 of the fibre in some cases into fibrillse, in other into discs, not unfrequently taking 

 place. 



We have looked carefully for a nervous system, and think that we have seen 

 appearances indicative of its existence. We slit open the animal along the dorsal 

 mesial line, and carefully removed the ovaries and intestinal canal. On examin- 

 ing the internal surface of the abdominal wall with a magnifying power of 200 

 diameters, collections of cells could be seen in many places. These were especially 

 manifest in the space between the roots of the two arms. These cells had many 

 of the characters of nerve-cells, such as delicate outlines, granular contents, aud 

 connecting processes. The processes from many cells were evidently two in num- 

 ber, though, from the close manner in which the cells were crowded together, it 

 was not possible to distinguish in some more than one process, and in others again 

 none could be observed. The investigation of the arrangement of the nervous 

 system in these creatures is evidently attended with considerable difficulties, 

 partly owin^ to the delicacy of the structures, and partly on account of the 

 strong ventral muscular bands and the gland-tissue surrounding the intestinal 

 canal, the presence of which interferes greatly with its due examination. 



If the female be carefully separated from the skate, and placed in clean sea- 

 water, we have found it possible, by occasionally changing the water, to keep the 



