278 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
He had previously described a single canal ; but, prompted by Pelseneer, 
has made further observations which have convinced him that they are 
multiple. 
5. Lamellibranchiata. 
Clasmatocytes in Lamellibranchs.* — M. J. Chatin describes pecu- 
liarly large cells which occur in the lacunar tissue of oysters, scallops, 
fresh- water mussels, &c. They measure from 100 p, to 300 p, are 
rounded, branched, or claviform, show a granular plasma, and emit large 
prolongations which habitually break off. They are comparable neither 
to the “ cells of Leydig,” nor to the Mastzellen of Ehrlich, but to the 
clasmatocytes which Ranvier first described in Vertebrates. 
Classification of Lamellibranchs based on the Gills.t — Mr. E. L. 
Rice has made an elaborate study of the gills as a basis for classifica- 
tion, and has reached conclusions somewhat different from Pelseneer’s. 
His scheme of relationships is the following : — 
Scrobicularia 
Tellina 
]> 
Donax trunculus 
j 
Capsa 
| 
Donax politus 
Psammobia 
Asaphis — 
Donax serra 
Petricola 
] 
Venus — 
—Tapes 
\ Yeneridae 
Cytherea 
' 
Cardita 
1 
Dreissensia 
1 
Cyprina 
1 
Astarte 
Mytilus 
OstreidsB Limidae 
I 
Anomiidae — j 
Primitive Astartidae 
? Odontopsis 
Modiola 
— Arcidae 
Aviculidae 
Pectinidae 
| 
Rkombopteria 
-Nueulidae 
Nuculoid Stammform 
? Nuculites and Praearca 
* Comptes Rendus, cxxiv. (1897) pp. 693-5. 
f Jen. Zeitschr. f. Naturwiss., xxxi. (1897) pp. 29-89 (2 pis.). 
