diff --git a/traittypes/traittypes.py b/traittypes/traittypes.py
index 516a91b..0346c15 100644
--- a/traittypes/traittypes.py
+++ b/traittypes/traittypes.py
@@ -213,6 +213,7 @@ class XarrayType(SciType):
     info_text = 'an xarray dataset or dataarray'
 
     klass = None
+    dtype = None
 
     def validate(self, obj, value):
         if value is None and not self.allow_none:
@@ -234,7 +235,7 @@ def set(self, obj, value):
                 not old_value.equals(new_value)):
             obj._notify_trait(self.name, old_value, new_value)
 
-    def __init__(self, default_value=Empty, allow_none=False, klass=None, **kwargs):
+    def __init__(self, default_value=Empty, allow_none=False, klass=None, dtype=None, **kwargs):
         if klass is None:
             klass = self.klass
         if (klass is not None) and inspect.isclass(klass):
@@ -246,6 +247,8 @@ def __init__(self, default_value=Empty, allow_none=False, klass=None, **kwargs):
             default_value = klass()
         elif default_value is not None and default_value is not Undefined:
             default_value = klass(default_value)
+            
+        self.dtype = dtype
         super(XarrayType, self).__init__(default_value=default_value, allow_none=allow_none, **kwargs)
 
     def make_dynamic_default(self):
@@ -274,7 +277,6 @@ class DataArray(XarrayType):
     """An xarray dataarray trait type."""
 
     info_text = 'an xarray dataarray'
-    dtype = None
 
     def __init__(self, default_value=Empty, allow_none=False, dtype=None, **kwargs):
         if 'klass' not in kwargs and self.klass is None:
@@ -282,4 +284,3 @@ def __init__(self, default_value=Empty, allow_none=False, dtype=None, **kwargs):
             kwargs['klass'] = xr.DataArray
         super(DataArray, self).__init__(
             default_value=default_value, allow_none=allow_none, dtype=dtype, **kwargs)
-        self.dtype = dtype