HISTORY OF RESEARCH. cxxxiii 



one for that part of the common chamber " which is capable of being broken off." 

 He therefore considers that it is " advisable to retain the word theca in its 

 original sense," and if a new word be necessary, to give one to " that portion of 

 the periderm which corresponds to an individual zooid once living within " (that is 

 to say the theca and its contributory part of the common canal combined). 



Although Tornquist agrees with Holm that the sicula is the covering of the 

 first zooid, he considers it very advisable to distinguish "in practice, between sicula 

 and thecaB," and therefore does not apply the term " first theca " to the sicula. 



Range and Distribution. — Tornquist prefaces his paper with an account of the 



seven Grraptolite Zones in the Rastrites Beds of Scania. These are very similar 



to those given by Tullberg, with the addition that the lowest zone, i. e. that of 



Diplograptus acuminatus, is here recognised in Scania for the first time. 



In 1897 Perner published the first section of the third 

 1897. 

 p ' part of his Monograph on the " Graptolites of Bohemia." 



" Etudes sur les Gran- This part contains a description of the species of Graptolites 



tolites de Bolieme," found in the lower layers of the band E. i., which corresponds 



Prague, pt. iii, to the Llandovery-Tarannon beds of England. 



Description of Species. — In the genus Diplograptus Perner 

 describes and figures the well-recognised species of Diplograptus palmeus, 

 D. bellulus, D. (Glyptograptus) vesiculosus, D. tamariscus, D. sinuatus, D. ovatus, and 

 D. modestus. 



In the genus Gephalograptm he includes G. cometa and G. folium. 



The genus Glimacograptus comprises G. phrygionius, G. scalaris, and the new 

 species G. bohemicus. 



Rastrites is represented by R. Linnsei (= R. fugax, Barr.), R. peregrines, 

 including two new varieties, var. longispinus and var. approximatus, and a new 

 species, R. Richteri. 



The group of Leptopodes in the genus Monograptus includes M. argutus, 

 M. attenuates, M. cyphus, M. limatulus, and a new species, M. tubiferus. 



In the group of the Orthopodes Perner describes M. leptotheca, M. Hisingeri, 

 M. crenulatus, M. SedgwicJci, M. Haiti, and a new variety of M. jaculum, i.e. var. 

 variabilis. 



The group of Helicopodes contains M. planus (=M. resurgens, Linnars.), M. 

 convolutus, M. proteus, M. triangidatus, M. turricidatus, M. communis and a new 

 species, M. mirus, Barr., sp. ms. 



In the group of the Opisopodes, Perner discusses at some length the exact 

 identity of Monograptus Beclci, and shows that Barrande had confused three dis- 

 tinct forms, all from different zones, under this single specific name. He refigures 

 the true M. Becki and also describes M. lobiferus, two. new varieties (var. Lapworthi, 

 and var. undulatus), M. runcinatus, M. crispus, M. dextrorsus, M. distans, M. 

 Glingani, M. (Rastrites) gemmatus, and the following new species : M. retusus, 



