ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 281 



1-2 mm. in length. The mouth is ventral, and the vas deferens, vagina, 

 and uterus open by a common posterior pore. There are no tentacles, 

 papilla, hooks, spines, nor skin-glands, but cilia appear to be present. 

 The digestive system consists of a spherical pharynx, a short oesophagus 

 with glands, and a rod-like digestive sac lined by a plasmodium. No 

 excretory system was made out. There is a distinct nerve-ganglion and 

 apparently two forward and two backward nerves. Ovary and testis are 

 both paired, and the yolk-glands are large and branching. A penis and 

 paired shell-glands are also present. The uterus contained a large egg. 

 The author also notes the occurrence of Nematode parasites in Echinus. 



Echinoderma. 



Abnormal Sea-urchin.* — W. L. Tower describes a specimen of 

 Echinarachmts parma in which the apical system is excentriciilly 

 placed, having moved away from the anus towards the opposite side, 

 but in a straight line ; the aboral surface, further, is almost bilaterally 

 symmetrical, and the ambulacral system v. is represented only by a few 

 scattered pores, which perforate plates of inter-ambulacral rather than 

 ambulacral character. These characters give the urchin considerable 

 resemblance to one of the Petalostichous Echinoids. Further, certain 

 of the plates showed complete fusion, and the genital plates and pores 

 were absent. The variation falls into class 2 of Bateson's classification 

 of echinoid abnormalities. 



Holothuria of Pacific Coast.f — H. L. Clark has worked through a 

 collection of 52 specimens of Californian Holothurians, including some 

 11 species, and reviews what is known of the Holothurians of that area, 

 which have as yet been very imperfectly studied. The Synapta of 

 California Clark believes to be merely the Atlantic S. inhserens. The 

 commonest Holothurian at Pacific Grove is Stichopus calif ornicus. There 

 are several (about seven) species of Cucurnaria, a new species of Thyone 

 (T. rubra sp. n.), and a peculiar form resembling both Psolus and 

 Thyone, which the author places in a new genus — Thyonepsolus ; it 

 differs from Psolus in the presence of pedicels on the dorsal surface. 

 The single species is Th. nutriens, which carries its young imbedded in 

 the soft skin of the back. 



Ccelentera. 



Mesenteries of Actiniaria.* — Oskar Carlgren describes as Pentactinia 

 californica g. et sp. n. an interesting new form, which lends new support 

 to his view as to the order of origin of the fifth and sixth pairs of 

 mesenteries in Actiniaria. In the new form the sixth pair remains in 

 an exceedingly rudimentary condition ; the relation of the parts is best 

 indicated by the following extracts from the generic diagnosis. The 

 mesenteries show a bilateral arrangement. There are only five pairs 

 of complete fertile mesenteries, which include two pairs of directive 

 mesenteries. On each side of the dorsal directive mesenteries there is 

 a pair of complete mesenteries with their longitudinal muscles facing 



* Zool. Auzeig., xxiv. (1001) pp. 188-91 (3 figs). 



t Tom. cit., pp. 162-71 (14 figs.). 



X Ofversigt Forhandl. k. svensk. Vet. Akal., Ivii. (1000) pp. 1165-75 (2 figs.). 



