1 882.] Zoology. 51 



stage, and it sometimes happens that there is but one embryo in 

 a capsule. The ova of this, like the preceding species are nearly- 

 opaque, and the walls of the stomach in like manner are composed 

 of very dark granular protoplasm. 



The next form of capsule observed, is that represented in Fig. 

 9, enlarged sixteen times, and is supposed to belong to the adult 

 represented in Fig. 8, enlarged five and a half times. These, as 

 stated before, were never seen to contain more than one embryo, 

 and measure over an eighth of an inch in length. The egg is 

 not so darkly pigmented as in the other forms. The supposed 

 adult of this species, Fig. 8, is apparently without eyes, and the 

 caecal diverticula of the stomach are arranged in a paired system 

 on either side of the median line independent of each other. 

 The peculiar hood-like cephalic extremity may be of the nature 

 of a sucking disk. This last form is milky white in appearance ; 

 the caecal prolongations of the stomach, yellowish. The stomach 

 in the other forms is dark brown, so that the two types of forms 

 may be at once distinguished. 



I do not propose to name the species, as these supposed distinct 

 life histories may, after ail our endeavors to separate them, be 

 only phases of the same thing. Sure points of distinction can 

 only be got by a more thorough study of these interesting types 

 than I have been able to bestow upon them, and I leave them 

 here in the hands of such helminthologists as may be disposed 

 to give the subjects of this notice further attention. 



I have not seen Dr. Graffs final p .per, in which P. limuli was 

 to be fully described and illustrated.— John A. Ryder. 



The Circulation of Sessile-eyed Crustacea. — Dr. Yves 

 Delage has published in the Archives de Zoologie experimen- 

 tale et generate, a superbly illustrated and detailed memoir on the 

 circulation of the sessile-eyed Crustacea. The plates are printed 

 in colors, so as to bring out clearly the heart, arteries, venous 

 sinuses and veins ; moreover, sections of the body are given, so 

 that the topography of the circulatory system is given in a 

 graphic manner. The memoir is too long for abstract, but it is 

 one of the most valuable contributions of the past year to our 

 knowledge of the Crustacea. The circulation appears to be on 

 much the same plan as in the Decapods. 



Viviparous Chirodota.— A Brazilian species of this genus of 

 Holothurians, or sea-cucumbers, has been found by Professor H. 

 Ludwig to be viviparous. The genital tubes appear to give rise to 

 both eggs and spermatozoa, the latter being developed in their 

 blind ends and lateral bunches. The young to the number of 

 sixteen, and all of the same stage of development, were found 

 lying freely in the body-cavity. They had seven tentacles, two of 

 them minute, and in the body-wall were groups of developing or 

 developed calcareous wheels. 



