September 4, 1003.] 



SCIENCE. 



311 



new name hy which to designate it. Stras- 

 burger's term ' spongy ' tissue, although given 

 when the nature of these cells was not under- 

 stood, and being a misnomer so far as their 

 structure and function are concerned, has 

 obtained a wide usage in the literature of the 

 gymnosperms and should be retained, just as 

 the term cell is still retained in all biological 

 literature. 



Margaret C. Ferguson. 

 Wellesley College. 



recext literature on trussic ichthyosauria. 



Within the past few months two important 

 contributions have been made to our knowl- 

 edge of the Triassic Ichthyosauria of the 

 Eastern Hemisphere. The more extensive of 

 these papers is one by Dr. E. Repossi,* giving 

 the long-desired exact description and illustra- 

 tion of the material upon which Baur based 

 the genus Mixosaurus. In this paper the 

 statements of Baur concerning the primitive 

 characters of this genus are strongly supported 

 and many previously unknown and even un- 

 suspected characters have been brought to 

 light. 



One of the most important contributions 

 made hy Eepossi is the description of the 

 pectoral and pelvic arches. These are quite 

 unlike those of anj- Post-Triassic form of the 

 order, but show a strong similarity to the 

 corresponding structures in the Californian 

 genus Shastasaiirus. All of the elements ex- 

 cepting the ilium and clavicle are much 

 broader and more robust than in Ichthy- 

 osaurus. The inter-clavicle is more nearly 

 triangular than T-shaped and is hence more 

 stegocephalian. The scapula, like that of 

 Shasta.<inurus, has more of a mosasaurian than 

 of an ichthyosaurian aspect. 



Beautifully preserved specimens show the 

 limbs to be pentadactyle with elongated 

 epipodial bones and notched or sometimes 

 shafted phalanges. A peculiar feature is 

 found in the presence of four elements in the 



* ' Em. Repossi. II Mixosauro degli strati tri- 

 asici di Besano in Lombardia," Atti drlla soc. Hal. 

 di sci'oi. imtiir., Vol. XLI., Fasc. 3, p. 361-372 

 tav. VIII., L\. Xovemb., 1902. 



proximal row of the carpus and tarsus. Were 

 it not for the character of the specialized 

 mesopodial region, these limbs might well be 

 considered as the primitive types from which 

 the limbs of Ichthyosaurus were derived. The 

 limb structure differs considerably from the 

 tj^pes found in the Californian genera, both in 

 the number of digits and in the character of 

 the mesopodial region. 



Another interesting discovery is the fact 

 that the dorsal ribs of Mixosawus are mainly 

 single-headed. Those who have concerned 

 themselves with this group seem generally to 

 have taken for granted a double rib articu- 

 lation. 



A second paper of interest dealing with 

 Triassic Ichthyosauria is one by N. Yakowlew 

 on ' New Finds of Triassic Saurians in Spitz- 

 bergen.'* One of the specimens here de- 

 scribed was found near the locality at which 

 the type of Hulke's Ichthyosaurus polaris was 

 discovered by Nordinskiold, and as it resem- 

 bles /. polaris in the size and general form of 

 the vertebrffi, it has been referred to this 

 species. A posterior dorsal vertebra which 

 has been figured is shown to differ from 

 Ichthyosaurus in possessing a single broad 

 apophysis for the articulation of the rib. This 

 species is, therefore, placed by Yakowlew in 

 the genus Shastasaurus. The vertebra is cer- 

 tainly very similar to some of the posterior 

 dorsals of Shastasaurus. After a study of 

 Hulke's descriptions and measurements of the 

 t.>'pe material, the writer has already expressed 

 the opinionf that a careful examination 

 would show it to belong in the Californian 

 genus. 



In this paper the valuable suggestion is 

 made by Yakowlew that the ribs of the 

 Ichthyosauria were primitively single-headed 

 and that the double-headed form has been jiro- 

 duced by more complicated and stronger move- 

 ments of the ribs, causing disappearance of 

 the middle portions of the rib heads and of the 

 corresponding parts of the lateral apophyses 



• ' Neue Funde von Trias-Sauriern auf Spitz- 

 l)ergen,' Verhand. der Kais. Ritss. Uineralog. (Jes., 

 Bd. XL., S. 170-202. 



t ' Triassic lolitliyopterygia of California and 

 Nevada,' p. 88. 



