S. L. Pen field — Crystallization of Herderite. 329 



In this table, the following abbreviations are used : Ant., an- 

 tenna; App., pairs of jointed appendages, either pediform or 

 branchial; M., Mandibie ; Mx., Maxilla; P., feet; M-P., feet 

 that serve also as jaws ; Mx. & L. (under Insects), maxillae 

 and labium ; Fol. P., foliaceous or lamellar feet or appendages. 



Under the Limuloids, the genus Eurypterus fails of antennae ; 

 but they are present in Pterygotus, and are chelate ; and this 

 chelate (or thumb-and-finger) form characterizes also the 

 modern Limulus, the Scorpions and the common Spiders. In 

 the table the two pairs of maxillse of Insects are assumed to 

 belong to a single body segment, as held by many zoologists, 

 including (as he himself informs the writer) Prof. S. I. Smith ; 

 the table shows that, with this admission, the thorax and head 

 of an Insect are essentially homologous with the head of a 

 Tetradecapod Crustacean. 



Art. XXXIV. — On the Crystallization of Herderite • by 

 S. L. Penfield. 



During the past summer Mr. L. K. Stone of Paris, Maine, 

 sent to Prof. H. L. Wells of the Sheffield Scientific School 

 several specimens of an unknown mineral for identification. 

 The specimens were collected at Paris, Me., but not at the 

 noted Mt. Mica locality. They presented well defined, trans- 

 parent and almost colorless monoclinic crystals, measuring up 

 to 2 mm in diameter and 6 mm in length. The crystals are im- 

 planted mostly upon quartz but some are on feldspar. Their 

 hardness is a little over 5. When tested before the blowpipe 

 they at first sprouted and turned white, but afterwards fused 

 at about 4 to a white, blebby enamel, tinging the flame very 

 pale green, indicating phosphoric acid. In the closed tube at 

 a high temperature the crystals whitened, threw off quite vio- 

 lently a fine scaly powder or dust and gave water which 

 showed only a faint acid reaction. The mineral was slowly 

 but completely soluble in hydrochloric acid. As these charac- 

 ters apparently did not agree with the description of any 

 known species, the mineral was supposed to be new and 

 accordingly the best material available for the chemical analy- 

 sis was carefully selected and eventually separated from any 

 attached quartz or gangue by means of the heavy solution. 

 The pure mineral, amounting to about one and a half grams, 

 and varying in specific gravity from 2 '936 to 2*968, was analyzed 

 by Professor Wells to whom the author's sincere thanks are 

 due. The analysis revealed the interesting fact that the mine- 



