NOTES AND LITERATURE. 



ZOOLOGY. 



Development of Cribrella. — The early development of the star- 

 fish Cribrella has been made the subject of exhaustive study by Dr. 

 A. T. Masterman. 1 Segmentation, which is very variable, always 

 culminates in a morula of equal cells. This becomes a blastula, 

 after which gastrulation takes place. The blastopore closes and the 

 archenteron divides into a mensenteron, and an anterior ccelom, and 

 a posterior coelom. The embryo then escapes as a free ciliated larva. 

 The posterior ccelom becomes the hypogastric coelom of the post-larval 

 stages. The anterior ccelom becomes differentiated into a central 

 ccelom, and a right, and a left lateral ccelom. The central coelom 

 becomes the ''dorsal sac"; the right lateral becomes the epigastric 

 ccelom ; and the left lateral the hydrocoele which eventually gives off 

 five radii. The bilateral larva loses its exact symmetry through an 

 enlargement of its left side. Fixation takes place and the unsym- 

 metrical larva is converted into a young starfish. The larval sagittal 

 plane corresponds to the discal plane of the starfish, the left side of 

 the larva giving rise to the oral, the right to the aboral side of the 

 adult. The bilateral stage suggests a bilateral ancestor similar to 

 Balanoglossus. 



Studies of Recent Brachiopoda. — Seldom has a single year 

 brought so many valuable additions to our knowledge of recent 

 Brachiopoda as are represented by the five papers that form the sub- 

 ject of this review. In fact, the only period that at all compares with 

 it is the year 1873, which saw the pioneer embryological work of 

 Morse and Kovalevsky. 



